Transition from an existing free community to a paying one, with management of founding subscriptions and automatic revocation of access for non-subscribers after a set deadline

I'd like to turn an existing free community into a paying one. To do this, I'd like to offer a founding subscription to existing members. Crucially, people who don't subscribe to this offer will automatically lose access to the community after a deadline that I could define. At present, there's no feature to automatically revoke access for existing members of a free community who don't subscribe to a new paid offer after a given date.