Well, this does surprises me. I have always been convinced that 1 LIC-AW covers 1 managed ip, so 1 switch stack should consume only 1 LIC-AW, not each physical switch.
Here is a quote form AirWave 8.2.2 Release Notes
"Licensing in AirWave
When you add switches to a stack, one AirWave license covers the switch stack. You can verify your license count
by navigating to AMP > Home > License."