Multi Volume license..

Bit of a question this one.
Has anyone made a system where the software makes sure it hasn't gone over the number of licenses on the network or something similar.

I want to know how many copies of the software are running over the network. I have software that can audit clients but don't want clients to run if the licensed limit is reached.

I'm not sure if a network license extension could be made. I could probably use mooclick connect to a server.

If you can run a server then it is as simple as connecting to it at the start of the application and having the server reject the connection if it already has more connected than licensed, and having the program refuse to run without a connection to the server.