Ultimate License: license key conflict

[unerwünscht]

I have an Ultimate License, and two of my users trying to log into tonight's game were getting a 'license key conflict' error, after downloading and installing without a license. The other 4 players logged in without issue.
How do you get a license key conflict when none of the players have a license key?

[unerwünscht]

I think I already discovered the issue. I believe my old license key was still in the registry on both systems. I will clear the reg files on them in the morning and test again.