Subscription Activate

To implement the Subscription activate API using the SDK, implement the abstract method processSubscriptionActivate from the PurchaseController:

         /// <summary>
         /// Proccesses Subscription Activation requests.
         /// </summary>
         /// <returns>A <see cref="Task{T}"/> of <see cref="SubscriptionResponse"/> or an exception if subscriptions are not supported.</returns>
         protected override Task<SubscriptionResponse> ProcessSubscriptionActivate(SubscriptionActivateRequest request);