If you wish to apply for a Master Observer's plaque, you need to register for ALCON 2022 by May 25. As part of the registration, you should indicate that you are a Master Observer, provide your certificate number, and state that you have not received the Master Observer plaque. You will also need to register to attend the Awards Banquet on 30 July, during which the plaques will be presented. You can register online or by mail.
The registration web page is: https://alcon2022.astroleague.org