AlarmBiller provides users with the necessary access (Administrators or User Administration permission) the ability to see if or who is currently logged into the software.
How to check if a user is currently logged into AlarmBiller?
Users with the necessary permission can simply click on the Setup -> Users option under the Company column:

Here, the status will display:

Note: This is accurate as the second it was accessed; To refresh the status, the refresh button on the bottom of the page can be used:

Administrators will see this option being grayed out when creating users, the field is not to give the online access to a user, it is simply an informational field.
Note: Online is strictly an informational field, is available when Administrators are creating users as being grayed out, it cannot be toggled to on or off or check-marked as enabled, since it is only an informational field that plays its role in the screen above and not when creating the user(s).