So you’ve just built a new PC, wiped your hard drive, or upgraded an older machine, and now you’re staring at that frustrating "Activate Windows" watermark in the bottom-right corner of your screen.
A: No. A digital license is a virtual entitlement stored on Microsoft’s servers. A product key is the 25-character code used to generate that entitlement. You don't need the key after activation, but it's good to have. how to activate windows 10 activation key
Click the Change product key link. (It may be labeled "Update product key" or simply "Change"). So you’ve just built a new PC, wiped
Click Next . Windows will verify the key with Microsoft’s servers. wiped your hard drive
Even with a valid key, things can go wrong. Here are the most frequent fixes: