Yeah, because running the AI also have some cost, so you are selling the subscription to run the AI on their server, not it’s output.
I’m not sure what is the legality of selling a bee movie maker, so you’d have to research that one yourself.
It’s not really a money making machine if you lose more money running the AI on your server farm, but whatever floats your boat. Also, there are already lawsuits based on outputs created from chatgpt, so it is exactly what is already happening.