when you leased a licence (I assume it is a so called named cal) from your server, it is "valid" for your QV-Client during 30 days of being absent, for ex. when your pc/laptop isn't connected into lan. At least after 30 days the licence should be renewed by reconnecting (once) to the QV-Server. This happens normally in the background every time when your client is connected to QV-Server (or can connect itself for renewing).
If you are "loosing" the licence more often, let's say every day, you should contact your local dealer or QV-support to see what's wrong.