Manage SSL certificates is for client-side certificates (something I have never used) and have nothing to do with your DLM license file.
I can't find a way to make that menu item disabled except if I haven't chosen a middleware option, then the menu item is not even displayed (though I am using ver 5.9).
Are you getting a license error or do you need to set up an SSL certificate for HTTPS scripts? I've setup plenty of HTTPS scripts and never needed to setup client-side SSL certs. What error are you getting?