A 13-year-old with access to his parent's iTunes account can potentially rack up a sizable bill in an afternoon of Candy Crush -- a tab mom might potentially refuse to pay because she didn't authorize the purchase. Payments company Oink has created a solution that lets kids buy what they want, but still stay within mom and dad's budget. With the service, parents can tie a credit card to the account and set limits on exactly where funds in the account can be spent, as well as how much money can be used in a single purchase. Oink works similar to PayPal in that purchases can be made online using just a username and password. A child could be given a certain amount of money to spend on their favorite game each month, or can be given an allowance that can only be used at a few specific retailers.