Designing an offline-first license system for macOS apps

I’ve been working on Keylight, a licensing layer for macOS apps, and one of the more interesting technical problems has been designing license checks that work both online and offline. The basic problem sounds simple: “Is this app allowed to run?” But in practice, there are a lot of edge cases: What happens if the user bought the app, but is currently offline? How long should an offline lease stay valid? How do you prevent a license from being copied forever? How do you handle device limits without making t