To upgrade the app, please follow the steps below:
1. Go to iOS Settings > iTunes & App Store > tap your account > Sign Out.
2. Reboot your device by pressing Home and Sleep button (Sleep and Sound down button for iPhone 7 or later) for several seconds till Apple logo is displayed to eliminate the temporary issues.
3. Sign in
4. Make sure there is enough free space on the device to fit the new apps.
5. Open Updates > Purchased > Scanner Pro > tap the Update icon.