If you are receiving this message it could be due to a number of reasons:
1. You are signed in with the incorrect Google Play account. Please sign in with the account that was originally used to purchase the app.
2. You are not connected to the internet. You should only need to do this the first time running the app after installation or the first time running the app after restarting your device.
When receiving this message we recommend that you reboot your device and ensure you are connected to a stable internet connection, ideally WiFi. Ensure you are logged in with the correct Google Play account; clear the Google Play Store cache and data. Then start the application again, in that order. To clear the data and cache of the Google Play Store application, please use the following steps.
1. Access your devices Application settings
2. Select the Google Play Store app from the list
3.Touch Clear Cache and Clear Data