My vMix registration key is for version 10; I recently installed windows 10, and I keep reading about the greatest and latest advances of vMix 17, so I tried buying the upgrade for $60.00, and the software wont let me upgrade. I downloaded a trial version, and I am loving the new version, do I need to buy a full registration key or can I have credit for the one I already have? Thanks for your time.

Yes, I logged on to http://www.vmix.com/account/ with my registration key; then I clicked on the "upgrade" bottom and I was redirected to http://sites.fastspring.com/vmix/product/upgrade. I submitted all my information, and I get an error message ""The key is invalid or does not not need to be upgraded"

I have the 2 copies of vMix in the same machine (v10 HD, and v17 Trial version); I don't want to reactivate the registration key in my account because then the system will assume that it is a second machine installation which is not.