NateJacobs

Expires a user’s access to a site after a specified number of days. It uses the user registered date/time and an admin configured number of days to determine when to expire the users access. The administrator can restore a user’s access from the user’s profile page.
There is a filter available for developers to hook into and alter the expiration date of a specific user on the fly during authentication. The filter uae_expiration_date passes the current expiration date and the WP_User object.

User Access Expiration

A user's access to a site is disabled after a specified number of days. The admin can set the number of days since registration to deny access.

Cyril Batillat

By default, WordPress can protect each post with one and only password. This plugin gives you the possibility to assign multiple passwords on each post, with an expiration date.

p5 : Plenty of Perishable Passwords for Protected Posts

Specify multiple passwords for pages / posts / custom post  types. An expiration date can be set for each password.

User Access Expiration vs p5 : Plenty of Perishable Passwords for Protected Posts