I can't confirm whether the suggestion in this thread Releasing Inactive Licenses in 10? works or not, but might also be worth a try.
If you don't mind the license manager restarting once a day, maybe using your OS tools to schedule the restart at midnight will help. However, if the software is open, but maybe just idle, a license will still be grabbed again.
By the way, I define a hung license as one that is checked out without the user having the software open. An inactive license, one that is sitting idle but the software is open, will continue grabbing a license, even if you forced a disconnect, unless you do as Curtis suggested with the options file, from my experience.