If your All Access Pass is activated via iLok and you're being asked to enter an activation code for Lustrous Plates when opening your DAW, your Lustrous Plates license could be in a cloud session in the iLok License Manager.
Lustrous Plates is a separate license activation from the All Access Pass collection
Sometimes Lustrous Plates is deposited directly to a cloud session, while the rest of your All Access Pass is on your iLok dongle
To move Lustrous Plates to your iLok, you'll just need to first close your cloud session from the "File" menu
Then you'll find the license under the "Available" tab within the iLok License Manager. Drag the license to your iLok on the left hand side of the iLok License Manager