I purchased Litchi for Android and P3P a few months ago. Have upgraded to Apple tablet, AIR 2, and new DJI P4. Went to download it from the Apple store and it said that I would need to pay for it. So my question is, do I need to pay for it again for the Apple tablet, AIR 2? If not, how do I get around sending the money to the Apple App Store and do a free download?