Relying on ads to monetize a kids' mobile app comes with a minefield of rules and restrictions. Apple, for example, requires app developers to avoid any behavioral advertising, ask for parental permission for in-app purchases and include a privacy policy.

Developers also must get parental consent before collecting personal information like phone numbers and email addresses from users younger than 13. Under a recent update to COPPA, the children’s privacy law, personal information now includes photos, videos, location data and persistent identifiers like cookies and mobile-device ID numbers as well.

Zuuka, a Santa Barbara, Calif.-based children’s app publisher, is approaching the challenge by delivering ads only to adults through a partnership with performance-based ad platform Tapjoy. Zuuka is the publisher of the iStoryTime app, which offers approximately 200 interactive digital children’s storybooks.

Through its partnership with Tapjoy, parents can earn points by engaging with ads they select from a list that can be exchanged for free books on the app. Users will be able to earn points, for example, by watching a video, filling out a surve, or liking a brand on Facebook.

“I’m a parent as well and there’s a lot of fatigue with apps that use in-app purchases in the freemium model, which is a good model, but when you do it on kids’ apps, there’s the problem of putting things in front of kids that they have to buy,” said Graham Farrar, creator of the iStoryTime app. “So we’ve given parents the ability to earn free content supported by advertisers, but in a way that the kids are never exposed to any advertising.”

The app uses a parental gate that requires users to enter a random set of words to enter the store. A separate password allows an in-app purchase. For now, users only have the option of buying books on the app. The ad integration will be included in an updated version of the app, which will come out shortly, according to Tapjoy.

In terms of targeting, the iStoryTime app does not collect data about its users or target its ads, according to Farrar. Collecting analytics or tracking information is “beside the point for us,” Farrar said. “We’re letting parents choose the ads they want to engage with and we just need to know how many points they’re earning.”

While it is not foolproof — it is not impossible for a child at an elementary reading level to pass through the store’s gate, especially on a reading app — creating a separate section for advertising offers more possibilities for advertisers on children’s apps.

“Advertisers would rather reach parents since they’re the ones who hold the purse strings,” said Rob Barnett, head of publisher development at Tapjoy. “What’s even better is that the parents can self-select the ads they’ll watch, which gives advertisers an audience that is more likely to be interested in what they have to say.”