Nowadays, you would be hard-pressed to find a free app that doesn’t include some kind of In-App Purchase. In-App Purchases, or IAPs, are app upgrades that can be purchased directly in the app. Due to their nature, IAPs, can easily be mistaken as part of a game, and may be money sinkholes just waiting to be triggered by an unknowing child. Luckily, they can be turned off by navigating to Settings -> General -> Restrictions. Set up a restrictions password if you haven’t already, navigate down to In-App Purchases, and turn it off.
Have fun with your iPad!