Whenever I'm asked how many FogBugz licenses are left, I'm a bit uncertain. I think it's because the wording on the Licenses page always throws me. At the bottom of the license table on the Licenses page, it says
FogBugz license check passed: You have licenses for 16 named users. There are currently 14 active users requiring licenses.
Looking at this, one might think they have two licenses left (16 - 14). However, on the bottom of the Users page, it says
Active Users: 21
Licenses Used: 13
The reason the "Licenses Used" is one less than the "active users requiring licenses" is due to the fact that FogBugz comes with one free license. The actual formula for determining how many licenses you have left is:
(licenses for named users) - (Licenses Used)
or in this case
16 - 13 = 3
Assuming I've got that right, you could eliminate all ambiguity by just changing that last sentence in the license table from "There are currently 14 active users requiring licenses." to "You have 3 licenses remaining."