A: Make sure that Google confirmed your purchase and e-mailed Purchase Confirmation to your bound Google account (e-mail). Sometimes Google Play services misbehave (long lasting bug) and provide incorrect reply to the application's request to validate license. You can try to fix it:
- Uninstall Neutron (settings will persist);
- Access OS settings -> Apps -> find Google Play Store app -> clear cache and data -> find Google Play services -> clear cache and data -> reboot device;
- Open Google Play Store -> find Neutron -> install and open it from the Google Play Store;
- Access Neutron's settings -> Help -> Account -> wait until progress bar stops and GOOGLE_PLAY entry gets red dot that will mean the success of the license check.
If nothing helps please send message to the technical support e-mail.