I travel ALL the time, so love that Spotify Premium lets me use my UK card to access anywhere in the world. But as I spend alot of time in Singapore, my Singapore phone cannot access spotify on the Market.
I don't see why you need to restrict the service AND the app.
This isn't a problem on the iOS App Store as Apple determines region by credit card address... like spotify. Google in their infinite wisdom decided that was too simple.
Please bear in mind that the Community is not an official Spotify support service. It's a place where we all help each other, whether we work for Spotify or not. So please use your discretion when using the forum.