It will have a global catalogue of songs, which are non-static. This means you can let them react to your environment or activities, but not necessarily. By leveling up, you can unlock new parts of the catalogue, new features, new filters. If you happen to have an amazing session with a non-static piece of music, you can save it, so you can hear it again or friends can listen to it. These types of activities help you level up and earn you virtual currency.