In DragonVale for the iPad, iPhone, and iPod Touch, while the game itself may be free, in-app purchases can make the game fairly expensive if you’re not careful.
If you’re a parent letting your kids play the game, then I would highly suggest turning off and passwording the option for in-app purchases to make sure you never get a shocking bill any time in the future.
Follow these steps to disable in-app purchses for any game on the iPhone, iPad, and iPod Touch.
1. Go to Settings from the home screen
2. Press General
3. Press Restrictions
4. Select Enable Restrictions and enter a password to keep anyone from disabling it in the future
5. Scroll down Allowed Content, and turn the In-App Purchases option to Off, which should prompt you for the password you setup