Using APK expansion files
Small applications that download quickly generally give the best user experiences. However, if your application requires more than 50MB of space, you can use expansion files to store additional APK assets. In addition to the original 50MB, Google will store two expansion files per application. Each which can be up to 2GB in size. One file will be the main expansion file and the other is an optional patch expansion file, usually used to provide small patch updates to the main expansion file. The expansion files can be any type of file and are saved to the device's shared storage location (such as the SD card or USB-mountable partition) where your application can access them. Every extension file URL issued is unique for every download.
Google Play hosts your application's expansion files at no additional cost. When possible, Google Play will download these files whenever it installs or updates your app. In some cases your app must still download its expansion files, but Google Play always provides the hosting, and code is provided for obtaining the URL and other download information.