You have 2 choices.
1) As KMT indicated, you could operate under 3.1.3 and sell the content outside of the app. The app is used just to 'read' the content:
3.1.3 “Reader” Apps: Apps may allow a user to access previously purchased content or content subscriptions (specifically: magazines, newspapers, books, audio, music, video, access to professional databases, VoIP, cloud storage, and approved services such as educational apps that manage student grades and schedules), as well as consumable items in multi-platform games, provided that you agree not to directly or indirectly target iOS users to use a purchasing method other than IAP, and your general communications about other purchasing methods are not designed to discourage use of IAP.
2) You can sell the content within the app using IAP.
>Should we use Non-consumable type or non-renewable subscription? If you want to make the material available for a fixed period of time then use a non-renewing subscription. If you want to make the material available forever then use the non-consumable. If you want to enable the user to purchase various things then you could use a consumable Token system wherein the user buys Tokens under IAP and your app debits their Token count as they make purchses.
> Can non-renewable subscriptions be valid unlimited time? No.
BUT - the app must function at some level (perhaps a 'lite' level) before the user logs onto the "ABC system" - that is, the app must function even if the user is not on the ABC system and has not purchased any IAPs.