@Jennifer976@Alex893 I've read quite a few hosts on this forum who take long term stays do recommend going in to clean once a week or two weeks (and of course making this clear to the guest when they book, and arranging a mutually acceptable time to do this when they are actually there), as this gives you a chance to make sure the guest isn't trashing the place out, keep the place in good knick, additionally if the guest knows you are going to be coming in to clean, they are more likely to make sure they aren't caught out living like pigs.
And the cleaning fees tied to a 2 week period sound perfectly reasonable.
It's your home, you have a right to create ways to minimize possible damage and dirty habits of a stranger. If a guest can't afford it, they can choose another listing.
If you see that a 3 month guest is actually very clean and tidy, you could always decide not to charge them for cleaning and let them attend to that themselves if they wish, after the initial 2 weeks or a month goes by, but let that be a pleasant surprise, rather than mentioning it beforehand.