Look in <instDir>/doc/license/license.pdf and search for the word "TIMEOUT". This describes how to set up license timeouts on the license server. The license can then be clawed back after a period of non-use. Note that when you start using it again in the session which has timed out, it will try to re-check out the license again.

The license should also get auto checked in when you close all schematic windows in Virtuoso.

Regards,

Andrew.