When an offer is about to expire, it is important to place an expiration date in the campaign settings.  Once a date has been selected, the campaign will expire at the close of that day.

Example:

Expiration Date: Aug 18, 2011

The affiliate's tracking links will cease to work at 12:00 AM, Aug 19, 2011.  If you would like to have an offer expire Sept 15, 2011, the date will be Sept 14, 2011.

Once the campaign expires, you can redirect all traffic by utilizing the Expired Redirect drop down menu.