Tell him as soon as he pays your bills for you, you'll stop. I don't know, I'd be really bothered if my husband wanted me to stop caming. I'd stop, but there's pretty much no chance he'll want me to since I've been doing it this long. Honestly though, I've been caming for nine years, and him being suddenly not OK with it would be what would really be bothering me.
It would really depend on why and their plans for the future.
I'm not saying that it would be a problem if it was a long-term plan, but it would be problematic if they didn't realise how it could limit their future employment - say they get a degree in teaching. Them not being able to get a job doing that could put a lot of stress on the relationship - and them not having researched that would say something about them as a person.
If I was with someone for a long time, and then at some point during the relationship they started that sort of work without telling me, I'd be miffed, but it would be the kind of thing I'd be over in a few days. If they were already doing it before we dated, I'd have no real right to be upset, after all, it's not really first date conversation, and then it immediately drifts into that gray area of when you trust someone enough to reveal a secret without it being too long before you revealed your secret to count as lying, which I recognize as an unfair situation.