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.

Fumiki Takahashi

TAROSKY INC.

You can enter expiration date on edit screen. 
This plugin runs cron every minute to search expired posts and make them <code>private</code>.

Taro Clockwork Post

A WordPress plugin to expire post with specified date.

User Access Expiration vs Taro Clockwork Post