This is a rare but unfortunate report that we've recently been made aware of. We have contacted the Android development team to understand what caused this in their code. We are doing what we can on our end to resolve this issue for those affected.
Meanwhile, please redownload SwiftKey from the same storefront you originally purchased it from. As long as you are signed into the same account that you originally used to purchase the application, you will not be charged a second time. Also, remember that to get SwiftKey fully installed, you may need to click on the SwiftKey icon in your app drawer to initialize the installation process.