Difference between the versions "FEFLOW Essential" and "Professional licence"

Hello,

Please, could anyone explain the difference between the versions "FEFLOW Essential" and "Professional licence"?
On the DHI website it is indicated that the difference is in the "limited" or "unlimited" number of simulations, but I don't understand exactly what does it mean.
I try to explain myself: if I want to build an aquifer model, once I have built the mesh, geometry, introduced the hydraulic parameters, etc., if I run the model, with the  "Essential" version, could I not calibrate the model and launch others runs or make modifications in the mesh?

Thanks in advance