I have a laptop with Win 7 Ultimate activated with daz loader. I understand that this is not legal though it shows as genuine and also updates. I was thinking of buying a Win 7 Pro license so that I can get a free upgrade to Win 10, because from what I have read, the pirated Windows will not upgrade. However, Win 7 Pro is not available on MS store in India and Win 8.1 is very expensive. Can I buy just the product key online from anywhere and change that in my laptop? Is a Win 7 purchased license transferable to another computer?