So ...

It's extremely simple ... In the plugin settings, you can set the maximum number of days users are allowed to use the same password (90 days by default), as well as which user roles will be required to reset their passwords regularly (non-administrators by default).

Upon activation, go to visit Users => Expire Passwords to configure the plugin settings:

As you can see, it's very straightforward ... You can define the number of days after which a user must change their password, and you can select the user roles on which this policy applies.

And that's it ... Click the "Save Changes" button and you are good to go ...

OK. Now let's see the result ...