Login day
From YPPedia
Login day is a day that a user logs onto his or her account. A login day covers 24 hours; i.e. logging on three times in one day does not equal three login days. Trial accounts on subscription oceans last seven login days, while rank badges on doubloon oceans last 30 login days.
It is believed that this is how decay for inventory items, such as swords and charts, is calculated as well.
External Links
http://www.puzzlepirates.com/community/viewtopic.php?p=286445#286445
