here is my "Problem", I have an Product with a one year Trial and the same product without trial. Is there a way to use only the Product with 1 year free trial and decide to who I give the trial? If there is a way, is that allowed? I want to give the trial only to people that has bought that product in Android. So they can use the same functions without buying the product again. I will tell them that they can cancel the subscription 1 day before the trial ends.New user will buy the product but the trial won't be given to them. I hope you guys can Help. Thanks.
Is it technically possible? Kind of. You could conditionally show only 1 of the 2 available IAPs to your users in your app's UI. However, in the App Store users will always be able to see all¹ In-App Purchases you have configured in iTunes Connect. So that might be a bit confusing for your users.
Is it allowed? That's more of a grey zone. The guidelines don't explicitly mention it but that is never a guarantee. There is mention of cross-platform considerations in the In-App Purchase Programming Guide, but it's more in the context of sharing functionality between macOS and iOS:
[...] You could let users who have a subscription in an iOS app access the content from a macOS app (or vice versa), but implementing that functionality is your responsibility. You would need a system to identify users and keep track of the content they are subscribed to, similar to what you would implement for an app that uses non-renewable subscriptions.
¹ : On iOS 11 you can choose to promote certain IAPs:
You can choose to promote up to 20 in-app purchases at a time on your product page, with additional in-app purchases approved and ready to promote. This gives you the flexibility to change the in-app purchases that appear on your product page at any time based on your business needs — for example, if you’re planning to launch a limited-time price promotion or offer exclusive content.
I'm not sure that will completely hide non-promoted IAPs though. I have yet to finish watching the What's New in StoreKit WWDC session :)