The WARN messages about selector threads should have been INFO messages; you can consider them just as improper logging.

The WARN message about "unregistered mode" notifies an error in your configuration of the free license. You should find more messages about license configuration at the very start of the log, above the reported snippet.

Anyway, this license issue causes the Server to run in a limited way, but it does not cause it not to run, as you say.
We need more evidence or a more detailed description of the issue that you are reporting.