You can find your product key on your computer or inside the Windows package—or in a confirmation e‑mail if you purchased and downloaded Windows 7 online. Go to the Microsoft website to see examples of product key stickers.
If you can't find your product key, you might need to buy a new one. To learn how, see Get a new Windows 7 product key. If you receive an error indicating that your product key is not valid when installing Windows 7, see Windows 7 activation error: invalid product key.