The method of payment has no bearing on the amount of access a subscriber receives. It is incumbent upon the consumer to understand precisely what he or she is getting for their money. Some subscriptions allow for access on any device so long as the proper sign-in and password information are provided. Other publications, the New York Times for example, require subscribers to specify, and pay extra, for each device on which the consumer wants to be able to view the publication. Subscribers to the print edition may access the online edition as well. Subscribers to only the IPad online version cannot view the newspaper on an IPhone or on any other computer. It all depends upon the package for which the consumer signs up.
With regard to payment options, online access typically involves online payment through the same payment mechanism used for purchasing apps. In fact, online payment is taking over the payment mechanism for most purchases of online content. Whether an ITunes stored value card is used as a method of payment has absolutely no bearing on options for viewing content.