If you create an organization, a plan (lock it), an API, and then publish it without having ANY client apps, you are then able to see the link in the API page where you can link a client app to it. If you click it, since there are no client apps, you get an error in the browser console and the dropdown for client apps is not there. You should not be able to see the link to link a client app / create a contract at all unless client apps exist.