What is the difference between a consumable, a non consumable, and a subscription based in app purchase, and how does each one genuinely differ in exactly how it should actually be properly handled by your app?

A consumable purchase, such as a genuine bundle of in game virtual currency, can genuinely be purchased repeatedly more than once by the exact same particular user, and your app is genuinely responsible for properly tracking how much of that purchased item a user currently actually still has remaining, a non consumable purchase, such as unlocking a genuine premium feature permanently, is only ever genuinely purchased just once and then remains permanently unlocked and available to that specific same user indefinitely going forward, and a subscription automatically and repeatedly renews itself on a genuinely regular recurring basis until the user actually properly and explicitly cancels it themselves.

// Consumable: user can buy again
// Non-consumable: purchased once, unlocked forever
// Subscription: automatically renews until genuinely cancelled