MicroKernal Users (#1) is no good as an indicator because Evo can spawn several processes per user.
The place Lynn said to look (#3) is the Pervasive licenses in use. We use Pervasive licenses with other programs (e.g. a label printing app, a Corrective Actions app, Excel, Evo2Web), but also have the RDP glitch, so that is not a good indicator for us. In your case, since you have nothing else but Evo using PSQL, it looks like the 17th Pervasive license is you trying to log in.
Selected File Handles for USERS.B (#2) should be your real number as far as Evo is concerned... one thing that I didn't know was how this would look if you also have DBA users logged in, so I tried it and it works the same.
Your actual usage should be 16, so if this is real time data, which it looks to be, I have no idea why that 17th user can't log in