App rejection - Code promotion

Context:

I am working on an iOS application designed for viewing comic books. This app features both a free and a paid tier (utilizing in-app purchases). We are keen on providing our users with an option to enter a code. Upon entering this code, users gain premium access to the content without any contractual commitment. This means that once the validity period expires, the premium access ends, and the user would need to subscribe contractually to continue. Our company fits under the App Reader category as specified in 3.1.3(a) (Link)

What We've Done:

We introduced a custom field in our application, allowing users to input a code. This code is sent to our backend, where it is cross-referenced with our database to ascertain its validity. If verified as valid, the user unlocks their right to the premium content.

The Issue:

Our application was rejected upon submission, seemingly contradicting section 3.1.1 of Apple's Guidelines (Link). Specifically, the passage stating:

Apps may not use their own mechanisms to unlock content or functionality, such as license keys, augmented reality markers, QR codes, cryptocurrencies, and cryptocurrency wallets, etc.

Apple's Recommendation:

We were advised either to remove the feature entirely or to utilize the code offer functionality available on App Store Connect. We had considered this, but it only applies to auto-renewable subscriptions (Link). Hence, it doesn't fulfill the condition we laid out in our context.

Our Proposed Solution:

Given our predicament, we're seeking validation on an alternative to avoid further costs that might result in another rejection. In order to identify our users (who are also paper format subscribers), we are contemplating the addition of a mandatory email field above our code field. Do you believe this would be sufficient?

A small clarification: the codes will be obtained through a marketing campaign via a contest, etc...

I'm not sure how adding an email address field changes the fact that you allow users to enter a code to unlock content or functionality?

Are there any apps you know of that do what you want to do? If not and if Apple says you can't do it, you will most likely need to change your requirements for this. If using App Store Connect code functionality doesn't work, you probably need to move the code redemption to your web site (like Marvel at https://marvel.com/redeem/ ).

App rejection - Code promotion
 
 
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