You can enter a product key during an automated installation of Windows® by including it in your answer file. However, a product key is not required for installing Windows.

If you do not enter a product key during installation, the activation clock gives testers and end users a 30-day grace period during which Windows activation is not required.

You can also use product keys to select an image to install during an automated Windows installation.

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Select Which Windows Edition to Install

To select a Windows edition to install, you can do one of the following:

  • Install Windows manually, without an unattend file. Windows Setup installs the default edition from the Windows product DVD.

  • Install Windows with an unattend file, and then manually choose which edition to install during Windows Setup.

  • Install Windows with an unattend file, and include a product key in Microsoft-Windows-Setup\UserData\ProductKey\Key. Each product key is specific to a Windows edition, for example, Windows 7 Home Premium. Entering the product key in this setting does not activate Windows.

  • Install Windows with an unattend file, and specify a Windows image in Microsoft-Windows-Setup\ImageInstall\OSImage\InstallFrom\MetaData. Use this setting when your custom .wim file includes more than one Windows image of a particular edition. For instructions on how to select a Windows image to install during Windows Setup, see Best Practices for Image Deployment.

For information about managing Windows product keys when changing the Windows image to a higher edition, see Change the Windows Image to a Higher Edition.

Activate Windows

To automatically activate Windows by using a product key, use the Microsoft-Windows-Shell-Setup\ProductKey setting. You can use either a single-use product key or a Volume License Multiple Activation Key.


The product key used to activate Windows must match the Windows edition that you install. If you use a product key to select a Windows edition, we recommend using the same key to activate Windows, so that the edition you install is the same as the edition that you activate.

If you do not include a product key, Windows prompts the end user for a product key during Windows Welcome. If the end user does not provide a product key, the activation clock gives end users a 30-day grace period during which Windows activation is not required.

  • When you are preparing to capture a Windows image for deployment, generalize the computer. Generalizing the computer resets the activation clock so that the grace period does not expire before the end user receives the computer. This is called rearming the activation clock. If the grace period expires, Windows prompts the user for the product key as soon as the user boots the computer.

    For instructions on generalizing the computer, see Prepare to Capture an Image for Deployment (Generalize).

  • If you do not use a Key Management Service, you can rearm the clock a limited number of times. For information about how many times you can rearm the activation clock or to delay rearming the activation clock, see Manage the Activation Clock.

See Also