It’s actually quite simple to turn off in-app purchases – simply go to Settings -> General -> Restrictions (enter your 4-digit security pass code) -> Allowed Content -> In-App Purchases and turn the thing to OFF! If you’ve not set a 4-digit security code on your iPhone, now is a good time as ever to do so. Kids love clicking various buttons on the iPhone touchscreen and you can never rule out the possibility of accidental app purchases, therefore it’s better to be safe than sorry. And trust me, accidental app purchases are fairly common especially with kids.

Usually, the in-app purchases require the iTunes password to be entered. But if you’ve already entered the password in the last 15 minutes even for a free app, the in-app purchase does not prompt for password again.