Questions about upgrading/reinstalling windows

[ItsDanish]

Hey, my screen keeps getting an error message 6-7 times a day. It says: Your PC ran into a problem and needs to restart. So i was suggested to do a clean install of windows 8. I was wondering to do clean install, Do I have to get a new key or can I just use the same from when I initially installed it. Another question, If I do the free upgrade from windows 8.1 pro 64 bit to windows 10, would it upgrade to windows 10 pro 64 bit? Thanks for your time

[ItsDanish]

6 minutes ago, Wheeljack699 said:

if you use the free upgrade and you are on win 8.1 pro 64bit you will get win 10 pro 64bit

if you are reinstalling on the same pc use your old key

thanks