Registering your account with an email will save your account progress to our servers in the cloud and also allow you to restore it later easily. Please follow the steps below. 

Register your existing account with an email and set a password to protect it
1) From your old device, tap to open the 'Menu' dialog
2) Go to 'Account' and tap the button 'Register'
3) Follow the instructions to bind your account with an email address and set a password.