MPU (d)

MPU — the average number of paying devices per the last 30 days.
On a daily basis, system computes the number of devices that have made at least one payment for the last 30 days. Average of the present measure for report period would be MPU.

Payment includes an in-app payment, subscription, subscription renewal, or custom revenue

In other words, MPU is computed using moving 30 days window. For example, if the report is aggregated by days, than MPU for 2023-01-26 would show the number of devices that have made a payment between 2022-12-28 and 2023-01-26.

This metric is more complicated than MPU in the classic sense.
Note new metrics MPU per month and MPU per 30 days

MPUFlow metric
MPU CACurrent Attribution metric