For an advertising agency, it would be a different client. For a real estate agent, a franchise location or an agent. Portals are compelling as they allow you to change between your different clients quickly.
As an example, an agency might have two clients. ABC Client and 123 Client. They would have two portals that are unique to each business but contained in your one Campaign Warrior subscription.
Having multiple portals means you don't have to continually log in and out of the program to manage your clients' content. Portals are a unique competitive advantage for Campaign Warrior and can be added at any time.
New Portals are $49 USD per month and added on a pro-rata basis as you add portals. Campaign Warrior provides you with a comprehensive billing report, breaking down your costs per client.