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 2021-10-20 would show the number of devices has been active between 2021-10-14 and 2021-10-20 inclusive.