Description: A practical look at how Mac developers can add license keys, device activation, and offline validation without building the whole licensing system from scratch. Keylight Tags: swift macos indiedev licensing security saas programming I build Mac apps, and one thing I kept running into was licensing. Not the fun part. The annoying part. You ship a paid app outside the App Store, then suddenly you need to answer questions like: How do I issue license keys? How do I know if a key is valid? How do I stop one key from being shared everywhere? What happens when the user is offline? What happens after a refund? Where do I store the license on macOS? How do I support trials without building a second system? At first, licensing looks simple. You imagine a table like this: license_key | email | status Enter fullscreen mode Exit fullscreen mode Then your app sends the key to your server and gets back: { "valid" : true } Enter fullscreen mode Exit fullscreen mode That works for a prototype.…