If for some reason an instance of HelpNDoc crashes without releasing its lease, the license server will think that the lease is still in use and will now issue another lease when requested: this could lead to an error message indicating that "There are no more free leases available from the floating license server".

Leases are usually updated every 30 minutes (configurable on the server side) and dead leases will be eliminated then. If that happens often due to hardware or software failure, it is possible to speed up the process by lowering the lease time from the server. See the <lease length="1800"/> option from the floating license server's manual to learn more.