You must've used a Hacktivator to activate it. Thats not the kind of stuff i recommend because it modifies your OS' files. Anyway, enjoy the 8.1 experience.
Well you could download the 8.1 iso, extract or mount it inside your current windows (i prefer extraction) and just run the setup. You will be given the option to keep or clean your files or data/programs on C drive.is there any way to download the 8.1 upgrade separately? it takes AGES to download from MS Store
I upgraded 8 PCs on my home this way and update process went perfectly smooth without any loss of files, settings or any software whatsoever.