Windows 10: Reinstall Windows 10 AFTER it was taken off (Windows 7 is currently on machine)

I purchased a laptop a few years ago with Windows 7 and then upgraded it to Windows 10. Windows 10 did not function well on the machine so I wiped the hard drive and reinstalled Windows 7. Now I would like to reinstall Windows 10, but I do not want to pay for Windows 10 since I already had it on the computer before. I cannot find any proof of the Windows 10 upgrade before, how can I reinstall 10 for free? I assume the product has to be tied to the serial number of my computer???


Thank you for your help in advance.

:)

 

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.

 

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

Yes, still work, no need to call, just be sure to have internet access when you start to install 10, I work at pc shop and did this few days ago, used a key of 7 to put clean 10(wasn't used for upgrade).

 

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

Your ild keys should work but if you registered the key to your online ms persona (email address) it should be tied to your account , install without a key login with your credentials , then activate.