The chage command changes the number of days between password changes and the date of the last password change. This information is used by the system to determine when a user must change his/her password.
adam@desktop:~$ sudo chage -l adam
Last password change : Mar 02, 2008
Password expires : Apr 11, 2008
Password inactive : never
Account expires : Mar 30, 2009
Minimum number of days between password change : 20
Maximum number of days between password change : 40
Number of days of warning before password expires : 7
Read the man page of chage here.