I am about to get my last part for my PC tmrw, now as for windows i will download the creation tool off of microsoft.com but for the key, i had a windows 8.1 to 8.1 pro i bought in 2016. I used it like 5-6 times when i used to have problems with my PC years ago to activate WINDOWS 10 PRO. I am thinking since i got it of off eBay is it safe to use now or will it even work. I know it has worked several times before but i am getting a bit worried