UPRIGHT PRO can work when the app is in the background or closed. With that said, each time you train you will need to use the app to connect to your UPRIGHT PRO and for calibration and stay within general vicinity of your phone.
After connecting through the mobile app, you may close the app and the device will continue to work. UPRIGHT PRO will continue to count your training time and analyze your posture. Upon returning to the app, it will automatically reconnect and update the clock.