WPU (d)

WPU — the average number of paying devices per the past 7 days.
On a daily basis, system computes the number of devices that have made at least one payment in the past 7 days. Average of the present measure for report period would be WPU.

In other words, WPU is computed using moving 7 days window. For example, if the report is aggregated by days, than WPU for 2021-10-20 would show the number of devices that have made a payment between 2021-10-14 and 2021-10-20 inclusive.

This metric is more complicated than WPU in the classic sense.
Note new metrics WPU per week and WPU per 7 days

WPU – Flow metric
WPU CA – Current Attribution metric