Set it to true (default) if you want N4 to purge the user login history in the Current Users Monitor view (on page 1) and the Authentication History view (on page 1) during each purge cycle per the ARGOPURGE039 (PURGE_AUTHENTICATION_HISTORY_DAYS_TO_RETAIN) (on page 1) setting.
Set it to false if you do not want N4 to purge the user login history.
For a multi-complex operator if you set ARGOPURGE007 to true for one complex, N4 purges the user login history for all the complexes.