Hello, I have an auto-renewable subscription with a duration of 1 year and a free trial of 14 days. Let's imagine a user that subscribes to this in-app purchase for the first time. After 14 days of free trial, he will be charged for the price of my subscription. After 4 months, he invites a friend to the app. I want to reward him with 1 month of free subscription time. Instead of the user being charged after 12 months after the first payment, can I make him pay only after 13 months after the first payment ? And if I can, how can I do that? Do I need to use promo codes? or promotional offers? or another thing? If I'm not being clear, feel free to ask me questions. Kind regards