This tutorial provides the steps to prevent unauthorized app purchases on Google Play Store. For this demo, we are going to be using the screenshots taken on Google Nexus 7.
Step 1: Tap the play store icon on your device.
Step 2: Tap the option icon available at the top right hand corner then select Settings from the menu list.
This should display the Play Store setting screen.
Step 3: In the Settings screen, scroll down to User Controls section.
Make sure to mark the check box with caption as “Use password to restrict purchases”. This should prevent unauthorized purchase of apps from Play Store. This is useful when you are sharing the Android device with your kids. And will prevent kids from inadvertently making any purchases.