: If you have already activated the key on a PC/Mac, simply sign in with your Norton account credentials on your mobile device to automatically link the protection. Important Tips
The most efficient way to activate protection on your phone is not by typing the key into the phone, but by syncing it with your account. product key for norton 360 mobile link
After the key is registered to your account, simply sign in to the mobile app to refresh the license status. Troubleshooting Activation Issues Change product key on Android devices - Norton Community : If you have already activated the key