All applications are Active in Sandbox by default, which is sufficient for testing them in the RingCentral Sandbox environment. Before a production key is issued and approved for an app, it is considered Blocked in Production.
In order to become Active in Production, you need to receive an active production app key. When your app is Active in Production, you are able to use your RingCentral integration with live RingCentral accounts.
Sometimes your application can get Blocked on Production after being Active for a while, or (very inlikely) - Blocked on Sandbox. This may happen if an application shows some unexpected and suspicious behavior in the sandbox or production environments. The RingCentral Support staff tries to solve these issues with developers first, but in some urgent cases your application might get blocked. If this happens to your app, you will receive a comment from RingCentral Support, providing the reasons for them blocking your app. After fixing all the issues, you can become Active on Sandbox/Production again by clicking the "Unblock application" button on the application basic page.