By default your Super Spell Heroes account only exists on your current device. If you lose that device or uninstall the game, your account might be lost.
To make sure you cannot lose your Super Spell Heroes account you can link it to a Game Center (iOS) or Play Games (Android) account. You can also link a Facebook account.
To login to any of these options, go to the player settings and check the status at the bottom of the options dialog.
You can also use linked accounts to continue playing on another device or even play on multiple devices.