Windows 10: WIN 10 activation after reinstalling

I had Windows 8.1 running on my PC then I upgraded to Windows 10. However I had to do a hardware change and Windows 10 disactivated.

Can you instruct me how to activate Windows 10 again. I managed to download it but the setup failed and Windows 10 has gone..

:)

 

active a win 10 reinstall

I got win 8 geniuene, then upgrade to win 10 for free. But now I must replace my HDD and reinstall win 10. How can I active it?

 

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

1 of my laptop has win 7, but not ufei so the key is not in the bios, but I did use the internet after I upgraded to win 10, so it's safe for me to just wipe and reinstall win 10 with win 7 key?

seems like my win 8 machine will be fine with the ufei thing.

 

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.