lol.. good luck... in MiCollab look at the License Info tab, but it is very deceiving since allocating a license to a user in MiCollab doesn't REALLY do anything I can see. We had an entire system of 500+ phones that a single license got assigned to a user in MiCollab and it worked perfectly.
Don't misunderstand, licenses are still required for things, but Entry/Standard/Premium licenses just dump more resources into the "pool" for the servers, but accounting for how a single license bundle is allocated is extremely difficult.
The answer is there is no report you can run that I am aware of.