When does memtest86+ stop?

It stops when you press Esc, I mean it loops until you stop it.

The number N of completed passes is indicated as Pass: N (it was Pass: 0 when the very first pass was running). I guess after 60 hours your N is relatively huge.

The message Pass complete, no errors, pres Esc to exit appears when the very first pass finishes without errors. If consecutive passes finish without errors, the message stays.

If there were errors, the program also loops. Either way it's your job to stop it. In case of errors there's almost no point of running additional passes. If there are no errors, running multiple passes is advised because there's non-zero probability that a faulty memory module successfully passes all tests. The more passes without errors, the more certain you may be your RAM is fine. In this case you stop the program when you think it's enough.

Also be aware that there is MemTest86 (the original version) and the MemTest86+ fork (which is not being maintained at the moment). They aren't the same software.

The current MemTest86 V7 release auto-terminates after 4 passes. It is a good idea to do at least 2 passes, as the first pass is a quicker less intense pass. This was a design choice done with the goal of picking up gross errors faster.