I did install and use windows 10 for 3 months and rolled back to windows 8.1 due to many issues(slow bot time,sound problem,Wi-Fi stability) on my dell 13 7000.And now I am planning to switch to Ubuntu as many of programs I use are already available in it.(Firefox, brackets, enpass, WAMP, phonegap, inkscape). or stay with windows 8.1 . So if later I switch to windows 10 after the end of free upgrade will it automatically activate with product key embedded in BIOS or will I lose it.