You can sign into your account on as many devices as you like, but as soon as you play any content, it will count as a registered device. You can have up to five registered devices. Please note that you can remove one device every 30 days. If you attempt to add another one, you will see the error message. You can remove one device every 30 days.
In case you encounter such an error, you can manage your devices from My Account page of TOD website or TOD mobile app. After removing one device as per the allowed limit, please retry playing content on the new device. If still facing the same error, sign out of the device and sign in back again to try again.