My purchase expired after the iOS10 to iOS11? – 有声双语小说-376部经典英文名著 Review

My purchase this app on July 1, 2017. It worked good with iOS10. After my device upgrade from iOS10 to iOS11, the app did not work. I emailed to ZhiQiao2012 about my situation, but I did not get any feedback. Right now, this app has upgrade to 4.0 and support iOS11. Unfortunately, my purchase seems expired. The cloud icon is grade up, and the app asks me purchase it again. Does it promise “Once purchase, Never expire.”? How you can fix it customers? Do I have to pay the app again if the iOS upgrade and the app upgrade?
Review by QRsearch on 有声双语小说-376部经典英文名著.