I have Air Navigation Pro for iOS, do I need to pay again for the Android version?
Air Navigation iOS and Android versions don't share the same license. They run under different Operative Systems and you need to download Air Navigation App store from different application stores. The code engine is different as well. That's why you need to purchase them separately.
For your purchased maps, charts, 3D data, subscriptions and other products, they are available to use on both versions without having to pay again. You just need to synchronize those products on a new device using your Xample account. If you don't have a Xample account, you can create it for free at https://services.xample.ch/.