/// <summary>
/// (UWP not supported) Upgrade/Downgrade/Change a previously purchased subscription
/// </summary>
/// <exception cref="NotImplementedException">UWP not supported</exception>
public override Task <InAppBillingPurchase> UpgradePurchasedSubscriptionAsync(string newProductId, string purchaseTokenOfOriginalSubscription, SubscriptionProrationMode prorationMode = SubscriptionProrationMode.ImmediateWithTimeProration) =>
throw new NotImplementedException("UWP not supported.");
/// <summary> /// (Android specific) Upgrade/Downgrade a previously purchased subscription /// </summary> /// <param name="newProductId">Sku or ID of product that will replace the old one</param> /// <param name="purchaseTokenOfOriginalSubscription">Purchase token of original subscription (can not be null)</param> /// <param name="prorationMode">Proration mode</param> /// <returns>Purchase details</returns> public abstract Task <InAppBillingPurchase> UpgradePurchasedSubscriptionAsync(string newProductId, string purchaseTokenOfOriginalSubscription, SubscriptionProrationMode prorationMode = SubscriptionProrationMode.ImmediateWithTimeProration);