Create in-app products and promotions

iOS - Creating In-App Purchases for Subscriptions – Mag+ Designd Support

Avoiding Apple's 30% Commission on In-App Purchases

Implementing promotional offers in your app

What are in-app purchases and how to increase them?

Android - Creating an In-App Product for Subscriptions – Mag+ Designd Support

Create In-App Products And Purchases For Apple And Google - Blog

iOS - Creating In-App Purchases for Individual Issues – Mag+ Designd Support

Not Showing Create Product in In-App products after Payment profile added - Google Play Developer Community

The complete guide to Google Play Store app optimization