While uploading you app to the Google Play Console, create In-app Products to enable In-App Purchase.
Open Play Console and go to the In-app products page (Monetize > Products > In-app products).
Click Create product.
Enter your product details :
Product ID : A unique ID for your in-app product. (make sure to plan your product IDs carefully. Product IDs need to be unique for your app, and they can’t be changed or reused after they’ve been created).
Note : The product ID android.test is unavailable for use, along with all product IDs that start with android.test .
Name : A short name of the item (up to 55 characters, but we recommend limiting titles to 25 characters to display properly in all contexts).
Description : A long description of the item (up to 200 characters).
Price : Enter a price in your local currency or select a pricing template
Save your changes and click Activate to make your in-app product available to users.
To be available for purchase, a product needs to be active and its app needs to be published.
If you’re using a test account, active items are available in unpublished apps. To learn more, go to the Android Developers site.
