At first you may think this app is dumb (and why pay..). But since we consume more and more music via streaming it is true that many titles of the catalog come and go and Apple will not notify you about this (blame it on music agreements and copyrights). I wish there was something like that on Spotify and i often discover huge part of my playlists gone, which pisses me off. Additions are also valuable. but hard to discover.
Zengo wallet
Sup app - Friends Nearby