Authorization is tied to the internal and individual ID number of each machine.
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Chances that the Authorization could get compromised by using up two or more of your three Authorizations with the same computer's ID number are all but nonexistent if the thing is coded properly.
I never used sampletank in 2013, so I thought I had to authorize it in 2014. When I did that, it said I had used up 2 of my 5 authorizations. I guess they didn't code it right.