If you need to activate a legitimate copy of Windows 7 Ultimate, you should use a valid 25-character product key.
: Check your confirmation email if purchased digitally from Microsoft Support , the COA sticker on your PC, or the original installation media packaging. Enter the Key : If you need to activate a legitimate copy
Enter your valid product key and follow the on-screen instructions to activate via the internet. the COA sticker on your PC
Scroll down to the section and click Change product key . If you need to activate a legitimate copy