I am curious about the implact on the gateway on a few modules that are in trial mode. From various searches I have come up with that when the 2 hour timer expires, cpu use stops on the module but continues to be loaded in Ram. Is this correct? Can the resources be seen somewhere?
No, reaction to trial mode expiring is entirely up to the module author.
The processor and memory usage of an installed module is negligible unless you're on an extremely resource constrained system. The first "thing" you configure that module to do is almost certainly going to have far more impact than the minimal impact of the module itself.
If you're in such a resource constrained system that you can't afford the few megabytes of RAM, you are not going to have a good time deploying Ignition - it is generally memory hungry.