Does the premium subscription limit the number of users that can use the account? The way we would use the application in our company would involve a single concurrent user, but several people would have access to the same account and use it at different times.
You are free to use a single premium account with as many people as you like. Several newsrooms do this already. NewsBlur should do a great job of keeping all of the separate clients in sync in real-time.
The limitation is simply all of the people using the same account share a single set of feeds and unreads, which makes sense.