Hi,
Please remember that you are paying for the number of seats. Many software packages, if you have 2 seats, will not even allow you to open a third copy at a time. Trusted licensing is nice. It comes into play if I don't check to see that all licenses are being used and I accidentally open Mstn on my laptop as well as my desktop. Or when I'm setting up new computers and have installed and am testing my installations. The bottom line is that if you expect to be using 3 seats at any given time, you should either have three licenses or you should postpone one session until one of the others is closed.
The one other comment I have is that Bentley logs in time frames (perhaps an hour). So if you have one computer with an active session, close it out, and then open it immediately on a different computer, it could count as an overage. You'd have to check with the Bentley licensing agreement to see if that is considered an overage or if it is just a false reporting of it.
--Robert