I have an app in the Apple app-store where some extra features are offered through a couple of one time in-app purchases. I want to transfer that to a subscription model. To make it more acceptable for those who already bought the old IAP I want to give them the first year free. However, I have problems implementing this.
Create an "Introductory offer" (one year free) for the new subscribed IAP. But I can't see a way to control who gets that offer, which means all new buyers will benefit from it.
Create a "Promotional offer". But that is only meant for getting old subscribers back. So there is no way for a new buyer to use that offer (I think).
Create two completely different IAP, one with an introductory offer and one without. That would work, but is a clunky solution that I want to avoid.
Are there any other alternatives?