To get the most out of Windows, it's important that you activate it on your PC. This way, you can take advantage of personalization and other features. Activation also helps verify that Windows hasn’t been used on more PCs than the Microsoft Software License Terms allow. To learn how to tell if your copy of Windows is genuine Microsoft software, see the How to tell page.
To activate Windows 7 or Windows 8.1, first you’ll need to find the product key for the copy of Windows that’s on your PC. Once you have that ready, select either Activate Windows 7 or Activate Windows 8.1 below and follow the steps.
If you have a volume license and want to activate Windows by phone, see Microsoft Volume Licensing Activation Centers Worldwide Telephone Numbers.