Windows 10: Windows 8 upgraded to 10. The I did full reset. Now asking product key to activate

I have the dell laptop which before has the windows 8 from the purchase. Then I upgraded to Windows 10 . And something happened i did the full reset using delete all files . Windows 10 installed everything alright but now its asking product key to activate windows 10 . What should I do now

:)

 

How to reinstall Windows 10 if my computers used the free upgrade from 7 and 8?

Will windows 10 still accept the license keys from 7 and 8 now if I reinstall my computer?

Does Microsoft keep a list of users who upgraded to Win 10 using their 7 and 8 keys so that when users need to reinstall windows 10 the old keys would work?

Do I need to call in Microsoft to ask them to activate my Windows 10 when I give them my win 7 keys?

Both computers are laptops. The windows 7 machine had the serial printed on the back, and I needed to enter that when I upgraded to 10. The windows 8 machine had the serial built in inside its boot system so I didn't need to enter the key when I upgraded to 10, but I did manage to write down the keys using a fetcher program.

 

win 10 upgrade asking for product key


An upgrade to Windows 10 running properly will not ask for a product key. Are you sure the version on the USB is the exact same version as the previous operating system on the computer you are trying to upgrade? Pro or home; N, standard, or Single Language Version? If you continue with an upgrade that is asking for a product key, it will not activate.

A clean install will ask for a product key, and that can be skipped. Unless you have purchased a license for Windows 10 that has it's own unique product key, you should never enter a product key when upgrading or clean installing Windows 10.

 

Windows 10 Upgrade Assistant asking for product key


So make sure that you are attempting to upgrade to the Home Single Language Edition. The "about" system settings screen will tell you if it is 32-bits or 64-bits (operating system):





Using the media creation tool, you want the matching 32-bit or 64-bit Single Language Edition:





From the Windows 10 ISO download site, it's just listed as Single Language Edition:





Doing an upgrade to the correct edition Anniversary Update should not ask for a product key.