I asked this same question in early October, and got a good answer, and my takeaway was to study the SAP reports some more, which I've done, and now I have some more questions.
This number (25) seems like the golden number, so if I reset Nov 1, when I check it on Nov 30 I'll see the max license usage I need. Assuming this month is average for a year, then I've got my number, right ?
It seems to me that if the number 25 is the golden number, I should have an SAP report that tracks this by minute, and then I could run this one report, look at the max, and there's my number to take to the boss to purchase licenses (appropriately trended over a year, let's say).
This is a custom Audit report, that looks at concurrent and named logons, with the peak being 30. Since it doesn't track logoff's, I think my 25 max licenses is valid.
The primary and additional tags were very hard to determine.