Licensing per userOne user needs one license, despite the number of computers they use. If a single developer works on multiple machines (workstations at work, laptop, home computer), they need a single license
The number of licenses doesn’t depend on the number of machines or virtualization
Licensing per SQL Server instanceEach SQL Server instance requires a license (e.g. if there are 3 SQL Server instances on a single physical machine, 3 licenses are needed)
The number of licenses doesn't depend on the number of machines, virtualization, or number of users
You can learn more about how ApexSQL tools are licensed
here