So I had the preview build, after windows 10 was officially released I was told all I had to do was install Windows 10 final version and skip when it asked for a serial. Checking everything, it has activated at all.

I tried this with my windows tablet same process other than coming for a preview build I was coming from Windows 8.1 and it was activated when I installed windows 10 final version.

Any help is appreciated. Thanks 😊