I've got a channel that used to be a free channel but then it was converted over to a subscription channel. In doing so, all previous viewers still get the channel free and new sign-ups are paid subscribers. Note that the subscription is not an in-app purchase, but rather the channel is set as a monthly subscription from within the developer console.
So the question is... Is there a way to tell, in the app, whether a viewer is a subscriber or a grandfathered-in free viewer? The reason that I want to know is for metrics purposes. I know that there is a ifChannelStore.GetPurchases() method but what I don't know is if this is applicable to subscriptions that are not in-app purchases. Also, if I use this function to successfully return purchase information, will I run into channel certification issues since my app does not use in-app purchases?