Not really, not to my knowledge anyways. I believe most if not all devs, regardless if the game is porn or not and regardless if they are indie or not, don't ask people to buy new updates every month. Only monthly subscription games like WoW actually asks you for that monthly $15.
I know that porn games get sold on steam without 18+ content and you can get the 18+ patch from the dev's actual store that unlocks it. But i've never heard of a porn game getting sold WITH 18+ content enabled and then selling a patch that removes the mosaic or whatever censorship they employ.
TLDR: No, just no.