By now, you might be aware of NPSettings. Incase if its new to you, read this post.
In your Unity project, If Billing is not enabled, enable by below steps. 1. Open NPSettings and select Application Settings. 2. Under supported features section, Enable Uses Billing checkbox and Save (see button at bottom).
Once you have Billing feature enabled, select Billing Settings. Let us take a brief look into it:
Products: Add the product identifiers for each platform you created in Registering your Products section. Later on, you can call NPSettings.Billing.Products to access this data from your code.
iOS Settings: Here, first thing you will notice is “Supports Receipts Validation”. This optional feature allows you to verify receipts of completed transactions. Enabling receipt validation, adds one more level of security to avoid unauthorised purchases. By default, our plugin contacts Apple Server to verify transaction receipts. However you are free to override this behaviour, by providing URL of the server to which receipt data has to be sent for verification.
For more information, see Validating Receipts With App Store.
Android Settings: You need to provide public key provided by Google Play services. This key is used for verifying signatures. For information on how to get Public Key, read Securing Your Application.
Thats it! Save all your NPSettings changes by clicking Save button at bottom of the inspector.