I'm currently looking into ...
Lic-Report
http://www.basic.si/lic-report/
JTM Flex Report
http://www.jtbworld.com/jtbflexreport/
OpenLM
https://www.openlm.com/?page_id=908
And this free program written by a member here
Aye I think they're the main options for monitoring licenses. Off memory they give you trend charts and metrics over time etc but by the sounds of it you just want to know who is hogging a license?
As well as the above programs have you considered an options files to run alongside LMTools to timeout licenses after a period of inactivity? That's what I do, 30 minute inactivity and the license is pulled back to the server.