Request for change password when expired

Hello folks,
I have few linux machines and one server from which I can connect to others without password (of course ssh key). On some server when root password will expired is asking me for change passord but on some servers no. When I can find some configuration of this behavior?
Thx for any tips.

Hi.

Not sure that ssh keys have anything to do with password policies per se, perhaps looking at /etc/login.defs, or this can help? If not a google search is bound to turn up something.