I think, as long as you can install the original B4X software, without the need for an online licensing system, you are good.
If B4X isn't available anymore (worst case of course), you still can maintain your applications. Ok, for new designs, you need to look for other options.
I like company's who gives you "your" licensed copy of the ide/software, as you buy it.
Also, when you PC is crashed, you can install the software again, without problems.
Sometimes, you can buy software with an usb-licensing stick, that is also a very nice way to have the software well protected for the software developer, while you as as enduser don't need to worry the day the developer stops this product/business.
All the systems providing SaaS (Software as a service ), for me, it's more tricky, if they stop their services one day to another, then you have a problem.
Today, big companies like Microsoft offering those services, no one is thinking about Microsoft that is stopping it's activity, but think what will happen if tomorrow all SaaS services are suddenly stopped.
Microsoft is also smart, they are now introducing "power apps" in office, to create simple programs fast., until you look at the pricing level per user / month $$$.
I think B4X has a lot of potential to grow, B4J as a RAD-tool (rapid application development).
The only thing they may not loose, is the simplicity, the B4X pages is nice, but for a beginner is gets fast too complicated. (multiple way's to make/start your project)
If you are "in" the evolution of the product, it seems easy for you, but new users can find it confusing (like myself).