We are currently offering a variety of premium plans on our app using in-app purchases and not Subscriptions. We have a 4 months plan and 1 year plan when user pays from the start (he can cancel at any-time by contacting us and our back-end manages the plans so after the period of the plan has ended he is downgraded automatically) and we want to switch this mechanism to monthly payments subscriptions for better revenue reasons.
It looks as (at least on Google Play) that we can define the billing period by weekly, monthly, etc, but the period of the subscription is still indefinit by meaning of time.
Are subscriptions are "for life" until user cancels it? How does it work?
Is it possible to create a fixed 4 months or 1 year subscription that is paid monthly until its finished automatically? How can we define that a subscription needs to end after exactly 4 months since user first purchase it? (It should also be auto-renewal month by month in that period).
If this is not possible, can we somehow create an indefinit subscriptions and "cancel" the subscription on iOS and Google Play stores for the user without him knowing? (from back-end or clients)
Also, what happens if user to buy a different subscription while he is already in one? Should he cancel and also then buy?
Thanks for any clarification. The official guidelines by both companies are no so clear.