I guess I have to go to the store now ;(
There's no reason to go complain to Apple store.
They're totally independent from Google Play Store, they don't have insight in your purchase there and even if they would have, they don't mind.
If you want to switch to some other platform, you need to purchase full license for that platform again, as you're dealing with completely independent store and company. This is only way.
If you stay with same platform, you could have game installed on as many devices as you want, as long as you use same login credentials (I'm not sure for Apple, but I'm sure for Google and Valve (Steam)).
In long run, if you start with Android phone, it is best to stay with Android, or vice versa, stay on iOS. Not only for purchasing software, but also for saving data (calendar, contacts, etc.) and retrieving it.
And, this situation with licenses is how it works for all paid software, EK isn't special in that aspect at all. Only thing different would be if David (developer) would have his own distribution company, but there are rare companies that in the same time distribute their own software exclusively on multiple platforms.