You can use SonicExpress to determine the maintenance key for an appliance, even if it has not yet been registered through MySonicWall.
The feature is only available for SonicWall next-generation firewalls.
To get the maintenance key for an appliance
Locate the QR code for the appliance you want to get the maintenance key.
The label containing the QR code may be found on the appliance or its packaging.
Scan the QR code with your mobile device.
Tap Enter Manually.
Tap Find It.
The maintenance code is displayed in the shaded area.