GN4 license is subject to expiration.
While you keep using the GN4, and the GN4 server is able to connect to Internet, the license will not expire.
When the Tera license server (default URL is http://licenses.teradp.com/lisa4Srv.asmx as it is defined in the GlobalConfig object as ServerUrl="http://licenses.teradp.com/lisa4Srv.asmx") do not receive any connection within a day from a GN4 server, it starts to decrease the 30 days of license validity.
The first time any GN4 application is used within this period, the license validity is restored to 30 days, unless the license is marked as cloned.
Important
If in an entire month a GN4 application is never used, the license will expire.
See also