Purchase using your Google Play balance
During the checkout process, select Google Play balance from the payment method drop down to pay using your balance. The item's purchase price will be deducted from your balance.
Your Google Play balance needs to be greater than the price of the item to use your balance. If your Google Play balance is less than the price of an item, you'll need to use a different payment method to complete your purchase.
Note: You can add to your balance by redeeming gift cards or purchasing additional credit. Google Play credit can only be purchased in the United States.
For more information about how Google Play balance can be used in your country, go to Google Play balance uses & restrictions.