If you have purchased the app but it cannot be installed due to license error, please refer to below steps to install again:

Android Devices:
  1. Go to phone settings
  2. Press Accounts and backup
  3. Press Manage accounts
  4. Press Add account 
  5. Press Google
  6. Sign in
  7. Install app again
Note: Please make sure that your phone is connected to a well worked Internet.