From the app:
- Tap More, then Manage account.
- Choose Unlock Plus and select I agree on the new screen.
- Sign in to iTunes and confirm your subscription.
From the Call Protect menu:
- Tap More (3-dot menu), then Settings.
- Choose Manage account.
- Tap Unlock Plus.
- Enter your myAT&T ID and password (only the account owner can add the subscription).
- Accept the terms and conditions for the Plus service.