SolidWorks can register idle time with the server so that licenses that have not been used for a certain amount of time are returned to the free license pool.
To monitor license idle time:
Create a text file:
<SolidNetWork_License_Manager_install_dir>\Licenses\sw_d.opt
Add the following line to the file:
TIMEOUTALL seconds
Replace seconds with a number greater than or equal to 900 (15 minutes), which is the minimum time allowed.