How do you count the number of user actions per session?

Question

Google Analytics

Colleagues, good afternoon!
I want to find out how many times the user performed N actions within the session (for example, paid for something in the service).
I take data about CLientID and users and filter them by an event that characterizes a certain action (for example, payment). Next, I take sessions with this event and divide them into unique users.
Who thinks about this method? What do you think of these metrics?