An Office 365 subscriber had a question about licensing:
I have Office 365 Business Premium. How many employees can I add to my Office 365 Business Premium license at no extra charge?
None. The Office 365 licenses on the business and enterprise side are per user. Each user needs their own subscription.
On the consumer side, Home Premium allows 5 installations and you can share those installs with up to 5 members of your household. However, Home Premium (and Personal) are not for commercial or business use.