Expire Nodes is a set of modules which allow you to set expiration periods per node-based content type.
You can choose whether to unpublish and/or delete nodes of a given content type, a given number of days after creation. Nodes marked Sticky are not unpublished or deleted. Nodes will be unpublished or deleted on cron runs, or any system event that triggers hook_cron().
This module is for Drupal 7. It has no dependencies other than the node module. It does exactly what it says on the tin.
Expire Nodes UI is another module in this package. It lets you configure the expiration periods per content type. It exists as another module so that you can disable it for production sites.
This project is similar to a few other projects. Neither Auto Expire, nor Node Expire are in active development, and both seem to have stopped at Drupal 6.
Scheduler is still under active development, with a D7 version.
How to use Expire Nodes module:
0) Keep in mind: THIS MODULE WILL DELETE CONTENT, so be careful testing it.
1) Enable the modules.
2) Go to the Content Types admin page: /admin/structure/types
3) Choose a content type to auto-expire and click 'edit.'