What is this process, “usagetrackingagent”, and why is it showing under activity monitor on MacBook
It is running on my three Mojave laptops.

BSD System Manager's Manual                      USAGETRACKINGAGENT(8)

NAME

 UsageTrackingAgent -- Usage Tracking Agent


DESCRIPTION

 UsageTrackingAgent monitors and reports usage budgets set by Health, Parental Controls, or Device Management.



Obtained from: https://www.unix.com/man-page/mojave/8/UsageTrackingAgent/