Since the App Management has been moved from Product to Admin > Site > Connected Apps, it is not easy to identify what App is paid (subscription base).

As per https://support.atlassian.com/organization-administration/docs/viewing-and-filtering-installed-apps/ we use lozenges to indicate some information, including "Paid Update".

It would add visibility and reduce administration efforts if we add lozenge for Paid (Subscription) Apps.

Current Workaround

All paid (Subscription base) Apps would have subscription in Billing. You may navigate to admin.atlassian.com > Billing and filter out subscription based on site name.