The Nexmo In-App SDK is a tool for building chat features into Android apps, providing better organization, maintenance, and weight reduction in code. By adding lifecycle-aware components, developers can separate concerns and create a more maintainable app. The process involves setting up dependencies, implementing a LifecycleObserver class to monitor the activity's lifecycle, and moving logic related to changes in lifecycle status to this new class. This results in a better-organized and maintained app that is easier for future developers to work with.