I installed yesterday and registered via this site. On your site when I am logged in it says my key is registered, but in my WP Dashboard when I load your plugin and press check for updates it says I am not registered.
Further down on this board I see someone had the same problem. You solved it by adding WWW to his url. I may have the same problem, I may have entered just the domain name not the www part of it. Can you please check? Thank you.
If you can see your registration when you are logged into gotmls.net but the domain name does not exactly match your site URL then you can just un-register your site, then go back to your wp-admin and re-register using the pre-filled registration form on the right-hand side of the Anti-Malware Settings page.