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Activating Windows

For more than a dozen years, desktop versions of Windows have included a set of antipiracy and antitampering features. In the past, Microsoft has used different names for these capabilities: Windows Activation Technologies and Windows Genuine Advantage, for example. In Windows 10, these features are collectively referred to as the Software Protection Platform.

The various checks and challenges in Windows 10 are, in essence, enforcement mechanisms for the Windows 10 license agreement, which is displayed during the process of installing or deploying the operating system (you must provide your consent to complete setup). We're not lawyers, so we won't attempt to interpret this license agreement. We do recommend that you read the license agreement, which is fairly straightforward. In this section, we explain how the activation and validation mechanisms in Windows 10 affect your use of the operating system.

Product activation happens shortly after you set up a new PC with Windows 10. Typically, this involves a brief communication between your PC and Microsoft's licensing servers. If everything checks out, your copy of Windows is activated silently, and you never have to deal with product keys or activation prompts.

In the past, activating Windows required entering a 25-character alphanumeric product key. On OEM PCs, this product key is stored in the computer's firmware so it can be automatically retrieved and activated. For retail installations and upgrades, though, entering that product key was mandatory. That's no longer true.

With Windows 10, Microsoft has made a fundamental change to the way it performs product activation on upgrades. The biggest change of all is that the Windows 10 activation status for a device is stored online. After you successfully activate Windows 10 for the first time, that device will activate automatically in the future, with no product key required.

When you upgrade from Windows 7 or Windows 8.1, the Windows 10 setup program checks your current activation status and reports the result to the activation servers. If your current installation of Windows is "genuine" (that is, properly activated), the Windows activation server generates a Windows 10 license certificate (Microsoft calls it a "digital entitlement") for the version to which you just upgraded (Home or Pro). That proof of digital activation is stored in conjunction with your unique installation ID on Microsoft's activation servers.

That unique installation ID is essentially a fingerprint of your PC, based on a cryptographic hash derived from your hardware. That hash is reportedly not reversible and not tied to any other Microsoft services. So although it defines your device, it doesn't identify you. But it does make it possible to store activation status for that device online.

Once that online activation status is recorded, you can wipe your drive clean, boot from Windows 10 installation media, install a clean copy skipping right past the prompts for a product key, and at the end of the process you'll have a properly activated copy of Windows 10.

If you're building your own PC or installing Windows 10 in a virtual machine that doesn't currently have an activated copy of Windows 7 or Windows 8.1, you'll still need a product key for use with a retail Windows 10 package or an OEM System Builder license.

After you successfully activate your copy of Windows 10, you're still subject to periodic antipiracy checks from Microsoft. This process, called validation, verifies that your copy of Windows has not been tampered with to bypass activation. It also allows Microsoft to undo the activation process for a computer when it determines after the fact that the product key was stolen or used in violation of a volume licensing agreement.

Validation takes two forms: an internal tool that regularly checks licensing and activation files to determine that they haven't been tampered with, and an online tool that restricts access to some downloads and updates.

If your system fails validation, your computer continues to work, but you'll see some differences: the desktop background changes to black (and if you change it to something else, Windows changes it back to black after one hour), an "activate now" reminder that also tells you your copy of Windows is "Not Genuine" appears on the desktop, and an Activate Now dialog box appears periodically. In addition, your access to Windows Update is somewhat restricted; you won't be able to download optional updates, new drivers, or certain other programs from the Microsoft Download Center until your system passes the validation check.

A device that has failed Windows validation can still be used. All Windows functions work normally, all your data files are accessible, and all your programs work as expected. The nagging reminders are intended to strongly encourage you to resolve the underlying issue. Some forms of malware can result in damage to system files that has the same effect as tampering with activation files. Another common cause of activation problems is a lazy or dishonest repair technician who installs a stolen or "cracked" copy of Windows instead of using your original licensed copy. Links in the Windows Activation messages lead to online support tools, where you might be able to identify and repair the issue that's affecting your system. Microsoft offers free support for activation issues via online forums and by telephone.

The activation mechanism is designed to enforce license restrictions by preventing the most common form of software piracy: casual copying. Typically, a Windows 10 license entitles you to install the operating system software on a single computer. If a system builder uses the same product key on a second (or third or fourth) device, you might be unable to activate the software automatically.

Entering a product key

When you upgrade a PC that contains a properly activated copy of Windows 7 or Windows 8.1, the freshly upgraded copy is automatically activated as well, with no manual intervention required on your part. At any time, you can check the activation status of your device from the Activation page in Settings, Update & Security.

In some installation scenarios, you might be prompted to enter a 25-character alphanumeric product key that uniquely identifies your licensed copy of Windows. If you experience activation hassles caused by an incorrect product key, you can use the Change Product Key button to set things right.

Here are some key facts you should know about this procedure:

  • The product key is entered automatically on any copy of Windows that is pre-installed on a new PC by a large computer maker. This configuration is called System Locked Preinstallation (SLP) and allows you to reinstall Windows from recovery media without entering a product key.
  • Your product key matches your edition of Windows. If you purchase a boxed copy of Windows 10 from a retail outlet, the installation media (typically a DVD) contains a configuration file that automatically installs the edition you purchased: Home or Pro. The product key works only with that edition.
  • Most Windows 10 upgrades don't require a product key. If you upgrade a properly activated copy of Windows 7 or Windows 8.1 during the free upgrade offer, you don't need to enter a product key. A record of the edition you're licensed to use, Home or Pro, is stored with your hardware ID on Microsoft's activation servers.
  • The architecture does not need to match your product key. You can use the same key to replace a 32-bit Windows 10 edition with a 64-bit edition, or vice versa.
  • You are not required to enter a product key when performing a clean install of Windows 10. You're prompted to enter a valid product key to install Windows 10 on a system that does not currently contain a properly activated ("genuine") Windows installation corresponding to the one you're trying to install. If you leave the Product Key box blank and click Next when attempting a clean install of an upgrade edition of Windows, Setup will not continue. You must click the tiny Skip link, just to the left of the Next button.

Activating a retail copy of Windows

When you install Windows 10 on a new PC, it will attempt to contact Microsoft's licensing servers and activate automatically within three days. If the activation process fails, you can activate Windows by connecting to a Microsoft activation server over the Internet or by making a toll-free call to an interactive telephone activation system.

Under most circumstances, activation over the Internet takes no more than a few seconds. If you need to use the telephone, the process takes longer because you have to enter a 50-digit identification key (either by using the phone's dial pad or by speaking to a customer service representative) and then input the 42-digit confirmation ID supplied in response.

The activation process is completely anonymous and does not require that you divulge any personal information. If you choose to register your copy of Windows 10, this is a completely separate (and optional) task.

You're allowed to reinstall Windows 10 an unlimited number of times on the same hardware. During the activation process, Windows transmits a hashed file that serves as a "fingerprint" of key components in your system. When you attempt to activate the same edition of Windows 10 you activated previously, the activation server calculates a fingerprint on the fly, using your current hardware setup, and compares the value against the one stored in its database. If you're reinstalling Windows 10 on hardware that is essentially the same, the fingerprints will match and activation will be automatic.

Just as with earlier Windows versions, the activation process is designed to prevent attempts to tamper with the activation files or to "clone" an activated copy of Windows and install it on another computer. What happens if you upgrade the hardware in your computer? When you activate your copy of Windows 10, a copy of the hardware fingerprint is stored on your hard disk and checked each time you start your computer. If you make substantial changes to your system hardware, you might be required to reactivate your copy of Windows.

Because the activation mechanism assumes (mistakenly) that you've tried to install your copy of Windows on a second computer, Internet activation might not work. In this case, you're required to manually enter a new activation code, which can be obtained from the telephone-based activation support center. You can upgrade almost all components in a system without requiring a new license. You can also replace a defective motherboard and retain the right to reactivate your copy of Windows. (If you upgrade your PC with a new motherboard, that is considered a new PC and might require a new license.)

Activation requirements for OEM installations

If you purchase a new computer with Windows 10 already installed on it, the licensing procedures are different, as are the rules for activation. In the arcane parlance of Windows, system makers are known as original equipment manufacturers, or OEMs. To make matters more confusing, not all OEMs are created equal; instead, they're divided into two classes:

  • Large system builders (Microsoft refers to these firms as named or multinational OEMs or, informally, as royalty OEMs) are allowed to install and preactivate Windows using System Locked Preinstallation (SLP), mentioned earlier. The preinstalled copy of Windows (including the recovery disc) contains configuration files that look for specific information in the system BIOS or firmware. As long as this information matches, no activation is required. A new computer from one of these large companies may contain a sticker that certifies your installation, but unlike in earlier versions of Windows, that sticker contains no product key. The OEM uses a single master key to activate large numbers of computers. If you need to reinstall Windows, you must do so by using the recovery media from the same computer (or one with the same motherboard/BIOS combination).
  • Smaller firms that build PCs can also preinstall Windows. These OEM copies are called System Builder copies, and they do require activation. The rules of the System Builder program require the PC manufacturer to use specific tools to preinstall Windows so that you accept a license agreement and activate the software when you first turn on the PC. In addition, the manufacturer is required to supply the purchaser with the Windows 10 media (typically a DVD) and affix a product key sticker to the PC's case. If you need to reinstall Windows on this computer, you must enter the product key and go through activation again.

The license agreement for a retail copy of Windows 10 allows you to transfer it to another computer provided that you completely remove it from the computer on which it was previously installed. An OEM copy, by contrast, is tied to the computer on which it was originally installed. You can reinstall an OEM copy of Windows an unlimited number of times on the same computer. However, you are prohibited by the license agreement from transferring that copy of Windows to another computer.

Product activation and corporate licensing

Businesses that purchase licenses through a Microsoft Volume Licensing (VL) program receive VL media and product keys that require activation under a different set of rules from those that apply to retail or OEM copies. Under the terms of a volume license agreement, each computer with a copy of Windows 10 must have a valid license and must be activated.

Enterprise editions of Windows 10 can be installed using Multiple Activation Keys, which allow activations on a specific number of devices within an organization, or they can use Key Management servers to activate computers within their organization. If you encounter activation issues with Windows 10 Pro or Enterprise in a VL deployment, contact the person in your organization who manages your VL agreement-the "Benefits Administrator" as this person is called.

Managing Windows activation from the command prompt

Windows 10 includes a command-line tool that you can use to examine the licensing status of a PC, change its product key, and perform other activation-related tasks. Although this feature is primarily intended for automating license administration activities, you can also run the Windows Software Licensing Management Tool interactively. Open a Command Prompt window with administrative privileges and then run the command Slmgr.vbs. Run without parameters, this command shows its full syntax in a series of dialog boxes.

One common use of this tool is to display the current licensing status for a device, using the syntax slmgr.vbs /dli.

For a much more detailed display of information, use the same command with a switch that produces verbose output: slmgr.vbs /dlv.