In-app Purchase Verification is a feature of the Facebook SDK that allows you to verify the legitimacy of every purchase made within your app. By validating purchase receipts with Google Play, you can ensure that the purchase data you see in Facebook Analytics or use to measure, target, or optimize your ad campaigns on Facebook is accurate and not distorted by fraudulent purchases.
1. Go to your app in the Facebook App Dashboard and select Settings > Basic in the left side panel.
2. Scroll down to the Android Platform card and toggle the Log In-App Purchase Events Automatically to Yes if you have not already.
3. Toggle Google Play Credentials to Yes to upload the JSON credentials file you downloaded to your local machine from the Google API Console.
4. Once the file has been uploaded click Save and the toggle will show Yes.
To change the verification credentials click the Update link in the Google Play Credentials section of the Android Platform card. You will be asked to upload the new file. Click Save to update the file.