I bought a subscription via Google Play, but now I bought an iPhone (or the other way around). Is my subscription automatically transferred?

No, you need to cancel the subscription via Google Play first, and then buy a subscription via App Store (or the other way around). Be sure to cancel your subscription, otherwise you will pay twice! Unfortunately Kitab Sawti can’t do anything about this, this is how Google Play and App Store work.

We are unable to cancel the subscription on your behalf.