The Licence Tester is designed to stress test your Licence Server and ensure you will have trouble free client licences.
First set up the Licence Tester Options, then Start the Tests.
Ensure the Licence Server has enough total primary licences to satisfy the number of client threads being created.
You should also ensure the Licence Server is configured to provide enough UDP ports to all the client threads. You will need a UDP port for every thread created as well as an additional UDP port if you plan to run the Licence Administrator simultaneously.