What do you mean? How can it be free if you have to pay for it?
I could be wrong but I don’t think they can charge a subscription due to Kodular being based on open source code (AI2). I think it’s part of the TOS that if you create a builder based on AI2 you can’t charge for the core functionality, but may do so for extras that you add yourself.
If I’m correct, AppyBuilder once use to charge for using their builder… or at least the “Gold” version. I’m pretty sure it just included monetization a, but I’m not too sure.