It gets stored on the adapter and will sync to your app the next time your phone and the adapter connect. Up to 8 hours of driving data can be stored from a 28 day period. Once 8 hours of unconnected driving is reached, the adapter will stop recording new data and must be synced to the app to dump the data off the adapter. This will happen on your next "connected" drive. Once it's in the process of syncing again, new trips can be captured. If you go longer than 28 days without syncing, those trips will not sync.