You technically need a 3 user licence, 1 each for the workstations & 1 for the server.

Don't know how much difference that will make though. I THINK you should be OK but will only be able to have 2 of the 3 open at once.

One thing I will say though is that Sage is a PITA some times when it comes to networking.

As long as you've installed it on the server 1st then restored the backup before installing on the workstations & trying to connect to the server you should be alright though.

Gareth