PAI Up requires you to set a PIN to secure your wallet, separate from your device passcode. You will be required to enter this PIN to view your balance or send PAI Coin, which keeps your wallet private even if you let someone use your device or if your device is stolen by someone who knows your passcode.
Do not forget your wallet PIN! It can only be reset by using your Paper Key. If you forget your PIN and lose your Paper Key, your wallet will be lost.