Every platform that takes a percentage will tell you what the percentage buys. It is worth reading that list carefully, because the answer is usually "payment processing" — which you can have for the processor's own fee, directly, today.
But the percentage is not the expensive part. The expensive part is that the buyer's payment is a relationship between the buyer and the platform, and you are neither end of it.
Three things that only bite later
Refunds are somebody else's policy
If a subscriber disputes a charge, the argument happens between them and whoever took the money. When that is you, you answer it with your own evidence and your own terms. When it is a platform, you find out how it went.
Payouts are a schedule, not your money
Money that has settled into your own account is money you have. Money in a platform balance is a promise, released on a schedule that can change, sometimes with a reserve held against it.
Leaving costs you your subscribers
This is the one to think about before you start. If the subscriptions were created under somebody else's payment account, they cannot be moved. No provider will hand a competitor your recurring billing tokens. Leaving means asking every subscriber to re-enter a card, and you will not get all of them back. A platform that holds the payment account holds the exit.
What "your own account" should mean
Not a sub-account, not a connected account owned by somebody else's platform with you as a beneficiary. Your account, in your name, with your keys.
The software should hold a key that can watch for payments and, when you ask it to, stop a subscription. That is the whole of the access it needs. It should never be able to move money to anywhere other than you, and it should be able to hand the whole thing back without asking anybody's permission, because there is nothing to hand back: the account was always yours.
The test is simple. If this software disappeared tomorrow, would you still be
getting paid? The answer should be yes.