How to add license keys to a SwiftUI macOS app (in under an hour)

Implementing license keys for SwiftUI macOS apps allows developers to sell software outside the App Store. Modern licensing systems focus on three core functions: activating a key as proof-of-purchase bound to a device, verifying that proof upon every launch, and managing feature gates offline. While older methods relied on local checksum keys and arithmetic rules, current secure desktop app licensing has evolved significantly, as detailed in the Keylight blog regarding SDK integration and activation processes.