You can preload (app only) available sessions in advance, ideally using a Wi-Fi network to avoid data charges. You can then play them when in airplane mode or when you have no internet connection.
To do this, tap on the little cloud icon near the session name to preload it (see the video).
When the session has preloaded, the icon changes to a smartphone symbol.
This allows you to play sessions on your phone wherever you are, even if your phone has no signal (indoors or in a basement space, for example) or if the signal isn't very good (on a bus or underground train). You can even choose to deliberately switch off the mobile or Wi-Fi network to avoid being disturbed.
To play preloaded sessions:
Simply keep the app open and tap the 'Play' button.
Smartphone and tablet media readers can't play the sessions as they have been encrypted to prevent illegal copying.
To delete preloaded sessions:
Tap on the drop-down menu on the left, then select 'My sessions'. Then tap the relevant smartphone icon to delete the session. If you want to delete all sessions at once, tap the dustbin symbol.