I am using Polaris Office Mobile on iOS devices, but I changed my device. How can I reinstall the Polaris Office Mobile app again??

1. Sign in to the App Store with the Apple ID you purchased Polaris Office Mobile.
2. As long as you sign in to App Store with Apple ID that you purchase the app, you can download it again at new devices.
(You need to download Polaris Office Mobile(No.2) in the screenshot.)