Activation helps verify that Windows hasn’t been used on more PCs than the Microsoft Software License Terms allow.
To activate Windows 7 or Windows 8.1, you’ll need a product key for the version of Windows that’s on your PC. A product key is a 25-character code that looks like this:
PRODUCT KEY: XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
How to find your product key depends on how you got your copy of Windows 7 or Windows 8.1:
For more info about how to tell if your copy of Windows is genuine Microsoft software, go to the Microsoft How to Tell website.
To activate Windows 7 using an Internet connection:
To activate Windows 7 using the phone:
Windows will automatically try to activate when you’re connected to the Internet. If you have problems activating online, you can activate using the phone.
To activate Windows 8.1 using an Internet connection:
To activate Windows 8.1 using the phone:
Article ID: 15083 - Last Review: 31 Aug 2016 - Revision: 53