Amazon Music Device API
A '“cache” is a local store of digital content or media that is requested in advance from the service to avoid unnecessary requests and reduce latency. For instance, when the user starts listening to a playlist the client might download and cache a chunk of the next track in the playlist before the user actually plays it, so that when they do, it can begin playing immediately. A distinction should be drawn between “caching” and “offline content,” which is where the user chooses to download media to make it available without needing to stream it.
You can cache the current track, the previous track, and the next track to speed up playback. You can also cache up to 30 seconds of additional tracks. In no case should cached files be accessible to the user for copying. All cached files should expire and be cleared if there is no connection to the Amazon Music service within 30 days at most.
Storing offline content is subject to legal and contractual limitations. Because of this, please submit a request in writing to Amazon to authorize any implementation of offline content storage. If Amazon agrees to allow offline content storage, all end user access to offline content must expire after 30 days of the user being offline.