You can save your progress by enabling the cloud save option in the game settings. Cloud save uses your Google Play (Android) or Game Center (iOS) account to save your current progress in the cloud. Tap on the Google Play Games/Game Center icon in the settings to log in with your account. If you change your device and download the game again using the same account, a pop-up will appear asking you to choose between restoring the progress saved in your account, or continuing with your local save on the new device.