If I understand you correctly, you wonder if the end users actually use all purchased toolboxes and how often.
I have seen the license('inuse') being used in a finish.m file and the results stored in a ASCII-readable file for further analysis. I recall this well, as there were legal discussions in that company, as the IT has not informed end users. So I would encourage you to think of this in case you role this out.
From a "running session", I can think of some options. I will reach out to the account manager of your organization and one of us will get in touch with you directly.