purchasePackage
Purchases a Package. If packageToPurchase represents a subscription, upgrades from the subscription specified by upgradeInfo's oldProductIdand chooses the default SubscriptionOption from packageToPurchase.
If packageToPurchase represents a non-subscription, upgradeInfo will be ignored.
Parameters
Current activity
The Package you wish to purchase
The upgradeInfo you wish to upgrade from, containing the oldProductId and the optional prorationMode. Amazon Appstore doesn't support changing products so upgradeInfo is ignored for Amazon purchases.
The listener that will be called when purchase completes.
Purchase a Package. If purchasing a subscription, it will choose the default SubscriptionOption.
Parameters
Current activity
The Package you wish to purchase
The listener that will be called when purchase completes.