So, after building my pc I installed the free version of windows 10. Since then I have been using it without an issue but was about to buy the USB installer and key. I figured before I did this I may as well make sure the window key that came with an old pre built pc didn\’t work. Much to my surprise, the windows 7 key on that computer (some Gateway pre built pc) activated my windows 10. Is this supposed to happen? I thought that a prebuilt windows key can only be used on that computer. Is it because I am using the same hard drive that was in the pre built? (This would be weird though considering that my OS is installed on an ssd.) Anyway, was that key supposed to work? (If so then I just saved 100 bucks.)
Sometimes they will work , but not always.