ARPU stands for Average Revenue Per User. It is the revenue generated by each active user over a given period of time. ARPU is mostly measured on a monthly basis. It is calculated by dividing Monthly Recurrent Revenue (MRR) by the number of active users.
ARPU = Monthly Recurrent Revenue/ Number of active users
It helps app developers understand the customer base and price strategy. It also helps to compare average revenue per user in different campaigns.