the average number of active devices per the past 7 days.
On a daily basis, system computes the number of devices tah has been active in the past 7 days. Average of the present measure for report period would be WAU.
In other words, WAU is computed using moving 7 days window. For example, if the report is aggregated by days, than WAU for 2021-11-30 would show the number of devices has been active between 2021-11-24 and 2021-11-30 inclusive.