You can install a license in your user account on any machine you use. The intent is that one of our apps will run concurrently on however many seats you purchase.
When one of our apps starts up, it checks the local network and sees if any other copies are using the same license code. (The apps do not phone home to us.) To facilitate syncing, we made a change a few months back where a 1-seat license will actually run on two machines at the same time.
When a third copy starts up on the same local network, it will do so in trial mode. That's what you saw happen.
Computers are really good at counting computers, and really bad at knowing that one fleshling is the person touching all three keyboards. If we had a good way to do the latter, the scheme would work differently. :-)
We're basically trying to find a compromise that allows individuals to get their work done, but doesn't enable a 10 person company to buy a 1-seat license and have everyone use it.
Upshot of all this is that what you saw when all three machines were active on the same network is what's supposed to happen. The circumstances are pretty narrow, though, and if it's a big problem, you can email
sales@omnigroup.com and they can lend a hand.