Auto_expire.ee2_addon is a project mainly written in PHP, it's free.
Automatically set an entry's expiration date for weblog entries in ExpressionEngine 2.x
Auto Expire adds the ability to any channel to automatically expire new entries. It adds a predefined amount of time to the entry date. If an expiration date has already been set, that date will be used as the expiration date.
Developed by Wouter Vervloet, http://www.baseworks.nl/
This version of Auto Expire is developed for ExpressionEngine 2.x
All the files and folders should be placed in an auto_expire folder the third_party folder:
/system/expressionengine/third_party/auto_expire/
/system/expressionengine/third_party/auto_expire/ext.auto_expire.php
/system/expressionengine/third_party/auto_expire/language/english/lang.auto_expire.php
/system/expressionengine/third_party/auto_expire/views/settings_form.phpAfter installing Auto Expire you alter the channel settings on the extension settings page.
The textfield is the number of minutes|hours|days|weeks|months|years to add to the entry date.