I'm sorry. You don't understand. The other plugin "Ajax Event Calendar" is just a normal plugin like many others. The settings for the plugin show on the left hand side panel where the other menus for admin show, such as "Tools" "Users" "Media" "Settings" etc. When I log in as an 'administrator' I can see the menu item "Calendar" under the "Settings" option on the left hand panel of admin. But when I log in as 'editor' (which is how my client would log in) then I can see the other menu options, such as "Media" "Tools" "Users" etc, but I cannot see the 'Calendar' option on the left hand options panel.
This is nothing to do any problems with the Calendar plugin. It's to do with your plugin NOT showing some menu options in addition to those that should show when an editor logs on.
I hope that is now clear?