I ended up just rolling my own a few years ago consisting of a B4J Server app done as a test and now I use it for almost all of my B4X projects and even switching over other apps, too. It started as just a test of authentication methods, in general, but then moved on to production use just authenticating app licenses. Now, it's morphed into a user-based and role-based authentication system, as well. Over the years, I've added tokens and a basic REST API in order to support some of the non-B4X apps of the company. Really quite handy and far more flexible controlling it this way.