Your game progress is saved automatically if your device is connected to the Internet. However, it may be lost if you reinstall the game.
In order to always be able to restore your progress, link your game to a social network account (Facebook/Google Play/Game Center/Apple ID). After you do this, you will always be able to load your game save if you sign in with the same social network account.
CAUTION! If you reset your device to default manufacturer settings, you will only be able to load your game save if it was linked to a social network account. The same is relevant for transferring your account to another device. (You must have your game account connected to Facebook if you want to switch device platforms [From Android to iOS or vice versa].)
How do I save my progress?
Tilting Point Support -