By default, the game progress is saved only on your device. However, if you want to have the opportunity to play with all of your accomplishments after reinstalling the application or on another device, you need to link your account to your Facebook page/Google Play/Game Center/Apple/MY.GAMES.

After that, to restore the progress you will need to only:
1. Install and start the game.
2. When you begin, log in using your Facebook/Google Play/Game Center/Apple/MY.GAMES.
3. Done!

If you choose to start a new game (the button "Play") and then log into your Facebook/Google Play/Game Center/Apple/MY.GAMES account in the settings, the game will offer you to restore your linked account.