Your data and entries are automatically stored on our servers. It does not matter which device you used for entering data. If you log in with the same user account, you will always have access to your fasting plan.
The synchronisation should also work if you have a new mobile or tablet. Just log back in with your user data on the new device.
If you want to use multiple devices at the same time, this is easily possible. Your data and entries are synchronized between the two devices. Please note that you may need to close the app completely and then reopen it for the updates to be displayed.