This could be done on Nanacast... However, it was not our intention that accounts be shared because of the increased demand on resources. Only 10k subscriber records are included with your account and after that each 1k is $10 per month.
URLs in our hosted content delivery system are cloaked using our own proprietary scripting; they are locked to an IP address, are generated user-specific, and locked with a key on our side. The URLs to the files cannot be used outside the system even if someone attempted to share them, when you use our built in Amazon S3 hosting integration.
This means as long the correct log-in credentials are used, then the content can be viewed securely, but URLs that are passed around won't work.
To restrict the IP addresses or the number of times a membership can be accessed: On the Edit Pricing/Delivery page there is an option to limit the number of IPs per day or per lifetime.
Keywords: Multiple logins