Licenses are attempted when the application (TestExecute or TestComplete) are started up. As far as I know, there's not an API call to the license server that you can call outside of those two applications. Simply starting the application attempts to consume the license.
I could be wrong... but I think that you may just need to tighten up your procedures for running automations to make sure that too many simultaneous executions aren't attempted.
Robert Martin [Hall of Fame] Please consider giving a Kudo if I write good stuff ----
Why automate? I do automated testing because there's only so much a human being can do and remain healthy. Sleep is a requirement. So, while people sleep, automation that I create does what I've described above in order to make sure that nothing gets past the final defense of the testing group. I love good food, good books, good friends, and good fun.