i wanted to know the safety of subscribing to 3rd party apps through the app store? i also wanted to know if we could use a iTunes gift card for the auto renewal subscriptions?

We wanted to subscribe to an app through the app store for our child. We just wanted to know how safe these 3rd party apps are with credit card information, because we dont want our information used in the wrong ways, or used for things other than the subscription. We also wanted to know if the subscriptions could be paid with itunes gift cards.