Spotify Offline Mode: do I need to launch the app within 30 days? (when I'm online)

If I use Spotify in Offline Mode on my iPad, I need to go online within 30 days or I will lose the offline songs.

But do I need to open the spotify app when the device does have internet connection, or can I just leave it close, and it will automatically inform the server?

In other words, do I need to take care about it and open the app when I do have connection, or this is done silently in background as soon as I connect to the internet (even with the app close) ?