I'm gonna need to move some of our ESXi hosts to another vCenter server and I've read the KB. But it doesn't explain how to handle the ESXi host licenses. Do I just add them to the new vCenter server and than remove them from the old one?
You are correct. I have done this dozens of times over the years.
Add the same license to the new vCenter
Add the host(s) to the new vCenter and assign the license
Remove license from old vCenter