Transfer subscription from iPhone to Android

Hi there. I've been a subscriber for a while now and have just changed from an iPhone to an Android device. I can't find a way of moving my subscription across to the Google Play store. Is this possible? The app keeps telling me to manage it in the iPhone app, but obviously I can't do that. 

I did cancel my subscription in the Apple store before changing phones, but the app doesn't seem to recognise that so I seem to be subscribing for free at the moment. I'd rather support it as it's amazing!