A: Each license allows you to build 1 community (with 1 custom domain).

So if you need a new domain for each brand, I'd recommend you purchase a license for each.

If all your brands can be rolled up under 1 domain, you can use our Groups functionality to segment out your community instead, and only purchase 1 license. Here's a quick overview video on how Groups work:
https://guide.heartbeat.chat/groups