I've found only this [old] related link in the forum, from 2015/16:
Software protection (apps created with B4J) - what's available ? | B4X Programming Forum
I'm looking for something that would work for my B4J application on Windows, MacOS and Linux (if possible). It's a
really critical component for a commercially launched B4J-based software product...or else
some -- cough, many! -- users can just get (AKA
steal) your product for free.
Note: License3j does not seem to be available as a commercial product any longer.