There is a license manager utility called swlmutil.exe. It is available on your client computers as well, but it has to be called from a command shell.
Please try the following: Open a cmd shell (cmd.exe) and enter
C:\<INSTALLDIR>\setup\swlmutil lmstat -f solidworks
with your SolidWorks installation directory as <INSTALLDIR>. You will find the info you are interested in in line 15 of the output, something like
Users of solidworks: (Total of XX licenses issued; Total of YY licenses in use)