When running multiple copies of 4D Server on a single machine, here is how the licenses work:

Built-in licenses:
Each copy of 4D Server normally carries two client connections. When several copies of 4D Server are running on the same machine, only two built-in connections are credited per machine. For example, if you run three copies of 4D Server on the same machine, only 2 built-in connections will be credited.

License sharing:
License numbers cannot be specifically assigned to a copy of 4D Server. Licenses will be shared on a "per machine" basis.

For example, if you bought a 10-user expansion pack and two copies of 4D server and you choose to run both at the same time on the same machine, you will be able to connect up to 12, 4D Clients at the same time. Each time a 4D Client attempts to connect to any of the two 4D Server copies, the connection will be accepted as long as the total number of connections for that machine is below 13.