Managing Application Access of a Media Playback System

A server comprising:

• one or more processors;
• and
• tangible, non-transitory computer readable media comprising instruction code stored thereon that, when executed by one or more processors of the server, causes the server to perform operations comprising:
• communicating a controller application and a certification message that includes a first validation-key associated with the controller application to a control device, wherein the first validation-key allows an instance of the controller application operating on the control device to schedule audio content for playback on a playback device of a media playback system until an expiration time;
• after the expiration time, communicating a second validation-key associated with the controller application and that is different from the first validation-key to the playback device, wherein the first validation-key is no longer valid for scheduling audio content for playback on the playback device;
• subsequently receiving, from the control device, a request for the second validation-key;
• and
• communicating to the control device the second validation-key to allow the controller application operating on the control device to schedule audio content for playback on the playback device.