Flag: Which users are using flag module's functionalities?

Here is a sql query that show users that use flag module's functionalities.

--Note: Depending on your drupal's installation, you may have to add prefix to table names.
SELECT name, DATE(from_unixtime(fc.TIMESTAMP)) FROM flag_content fc LEFT JOIN  users u ON u.uid=fc.uid;

It is good to know this statistic so that you can decide whether to remove this module or not.