The steps below will help you use the Change Product Key feature already included with your installation of Windows 7. If you bought an edition of Windows 7 other than what is on your machine, you cannot use this feature. For example, if you purchased Windows 7 Home Premium, and Windows 7 Ultimate is on your machine, you must perform a custom install.
Can't locate your product key? If you ordered a Get Genuine Online Kit, see the Order Support page for examples of where to find your product key. If you did not order a Kit, see other examples of where to find a product key.
Change your product key and activate Windows
Click Start , and then right-click Computer.
Click Properties.
Click Change product key at the bottom of the dialogue box.
Note: You may be prompted for permission to continue if User Account Control is enabled. You must press Continue if you wish to continue.
Follow the prompts in the dialogue box to change your product key and activate your copy of Windows 7.
Validate your copy of Windows.
Validate Windows to complete the product key update process. Validation is required for full functionality of Windows 7. Until you validate, not all features will be available.
