I purchased 3 copies of Win8 Pro upgrades whilst the low price offer was available and installed them on our 3 computers (2 desktops and a laptop). I (carelessly) didn't keep a record of which product key I used to activate each computer and decided to tidy up my records in case I have to carry out a re-installation in the future. I used Belarc advisor to reveal the Windows 8 product key on each computer - but I am surprised to find that none of them correspond with the keys I was given by Microsoft to activate Windows 8 during installation. Hence I am unsure which key I will have to use for a future installation - can anyone please clarify.