How to get an API key

Hi,
I bought the anti-splog plugin this morning and have read the install doc's and the help forum. I can't figure out how to register my IP address. When I click the link from the plugin (Get your API key and register your server here), I get a page with this message "You do not have sufficient permissions to access this page. I thought I could buy and activate this plugin without being a premium member?

thanks