FlexSim does not currently support borrowing from a server-based ("server-concurrent") license.
The best solution is to convert one or more seats of your server-based license into a standalone ("client-activatable") license. This will allow a client PC to activate and return the license at will. Once activated on a client PC, the license does not have to maintain a network connection.
We can help you convert seats to or from standalone or server-based licenses. Please contact your local FlexSim distributor to arrange such a conversion. The process will require you to return your licenses so that we can make these changes.
Be aware that pricing can differ for standalone vs server-based licenses. Contact your local FlexSim rep for details regarding your own licenses.