If the number of users per account is an important metric for you to track (for example your pricing is based off of # of seats/users using the account) you can do so by creating a calculated metric in the Usage Module.
If you just want the total count of users and contacts in the account, you can use the metric in the Data Module > Metrics > Company System Metrics > Number of Users.
Here is how you would set up the equation:
{"type": "metricOverTime", "prop": "system.users_total"}
**Always, when creating a calculated metric and specifying which metric/activity to use, use the EXACT spelling, spacing, and capitalization that displays.
However, when creating calculated metrics from the System Metrics, use the following:
system.users_total (for Number of users)
system.activity_count (for Activity Count)
system.users_active_last1 (for Users active last day)
system.users_active_last7
system.users_active_last30
system.users_active_last90
Let us know if you need any help setting up new calculated metrics for your business.
Being Alerted of Overuse
This is a great calculated metric to create because you are able to be alerted if the company is above their # of seats.
To do this, you can create segments for the # of seats sold (which can sometimes relate to the price level package they have purchased). Then, create an automation to be alerted for when a company in that segment rises above that threshold.
Read here for more ideas on how to segment your customers in Planhat.