<?php echo S2MEMBER_CURRENT_USER_DOWNLOADS_ALLOWED_DAYS; ?>
This will output the number of days (the period) in which stats are being kept.
(users are allowed to download X number of files every X number of days)

---- s2member Shortcode Equivalent ----

[s2Get constant="S2MEMBER_CURRENT_USER_DOWNLOADS_ALLOWED_DAYS" /]