When you want to find out who's using up all the licenses, you can run lmstat -a do find out.
Specifically, with Mac COMSOL, I do:
> cd /Applications/COMSOL43a/license
> maci64/lmstat -a -c license.dat
Users of COMSOL: (Total of 5 licenses issued; Total of 1 license in use)
"COMSOL" v4.3, vendor: LMCOMSOL
dmassey c22042.local (v4.3) (ancha/1718 1074), start Thu 12/13 18:26