System Variable 708: Allow to Re-Use Old Passwords: How Many Passwords Should the System Look Back On?
Use this System Variable to specify how many times users can reuse previous passwords.
For example, if the value of this System Variable is 2, users cannot reuse a password that they have already used twice. They must enter a completely new password.
The default value for this System Variable is zero, which means users cannot reuse any of their previous passwords.
Parent Topic: System Variable Grouping: Login & Password Policy