I have currently windows 8 running. I know I wont be able to upgrade to Windows 10 directly. I will be upgrading via create installation media (DVD). I tried via store previously and again rolled back because it would prompt me that some files are missing, although the OS was working but I had system metro apps broken so upgrading via DVD iso. Now my question is : I have windows 8 genuine copy which came preinstalled by my OEM (HP) and I dont have serial key. If the installation asks me for a key where would I get it from. 2. Would using programs which identify our OS keys are safe? 3. If they misuse my key and somebody would use that key to upgrade to Windows 10 before I do is that possible?