I'm looking to upgrade my pc to Window 10 using my Windows 7 key. However, because I'm stubborn and want to keep windows 7 a little longer, I'm also looking into dual booting both for awhile. I've found a lot of info on how to do this, none of which really says what happens to your Windows 7 key. I did find one site that mentioned the Windows 7 key expires after 31 days of upgrading. Is this true? Or can I continue to use both Windows 7 and 10 fully activated on the same machine indefinitely?