May I ask how you're able to make a living for several years with only 400 students? Do you sell each course for like $500 or more?
Ionic Academy is a good example I can think of, I was a member for just under a year, super helpful and regular content and probably doesn’t need huge amounts of members to be viable
I prefer to buy/offer a high value course with a price that matches it. I bought several of such corses myself in the past years.
I do offer payment plans for people that can't pay a big lump of money at once, but that's not a subscription they can stop. They still have to pay all installments.