Zendesk Enterprise includes a maximum of 5 brands, and you can add this to Zendesk Professional.
Our Enterprise clients that need more than 5 brands can purchase Unlimited Brands as an Enterprise add-on.
The PRO Multibrand add-on (max 5 brands) costs €25/license/month (minimum purchase equal to 10 licenses, so €250)
The ENT Unlimited Multibrand add-on costs USD€40/license/month (minimum purchase equal to 50 licenses, so €2,000)
Why add multibrand?
Support multiple business units (brands, products, service tiers, or regions) from a single Zendesk instance. You can create unique Help Centers, support channels, and business rules for each brand.
For a deeper dive, check out this one-sheeter about Multibrand