What is the developer payload?

[saldous]

I've tried with my Base64 encrypted key & my app package name and both return zero products, so must be something else.

[mradzinski]

The field developerPayload is a legacy field, kept to maintain the compatibility with old implementations, but as mentioned on Purchasing In-app Billing Products page (https://developer.android.com/training/in-app-billing/purchase-iab-products.html), this field isn't always available when completing tasks related to In-app Billing.

If you rely any important implementation of your in-app billing logic on the developerPayload, its recommend you change this approach, because this field will be deprecated at some point (or soon).

More information: https://issuetracker.google.com/issues/63381481