Ok so I had an original computer with windows seven, I bought it with the OS already installed and I didn't get the windows key, I upgraded that pc to windows 10 and have now built a new PC. I moved my drives and ssd with windows already on them over to my new build but now windows is telling me I need to avtivate windows by entering a key that I dont have, is there a way to get a key or do I have to buy a new OS