1. Log in to your Google Play publisher account: https://play.google.com/apps/publish
2. In the All Applications panel, click on the app name then select In-app Products
3. Click Add New Product and provide details about the item you are selling and then click Save or Publish
4. Enter specific details about this new in-app purchase, then click Save and select Activate
NOTE: You must enter the following information for each item in a product list:
> In-app Product ID
If you are unsure of what this is, you can view an existing in-app purchase product, or contact your Support Manager. Note that you cannot modify an item's product ID after it is created, and you cannot reuse a product ID
You must provide a default price in your home currency. You can also provide prices in other currencies, but you can do this only if a currency's corresponding country is listed as a target country for your application.
To specify prices in other currencies, you can manually enter the price for each currency or you can click Auto Fill and let Google Play do a one-time conversion from your home currency to the currencies you are targeting.
For subscription items, note that you cannot change the item's price once you have published it.