You can do this with chuser
see man chuser - maxage and maxexpired
force users to change passwords every 1 or 2 months, if a users hasn't logged in and changed it by maxexpired the account is locked.
Mike
"Whenever I dwell for any length of time on my own shortcomings, they gradually begin to seem mild, harmless, rather engaging little things, not at all like the staring defects in other people's characters."