For your case, I think there might be an “implied” standard that Marketplace kinda-sorta expects you would run a Free App and a Paid App, and that your app will “fall back to Free”. While that’s a pretty common pattern for modern SaaS apps (including most of Atlassian’s), that can be a difficult to pull off if you are a brand new vendor. As far as Atlassian is concerned, you can just “turn off” in the face of delicensing events. I think the Licensing FAQ is the doc with the major bits of guidance.
To be clear, that’s a different dimension than the new JSM feature is meant to handle. Similarly, there’s discussion playing out now for Confluence guest users in RFC-9 that explores yet another dimension.