Set Wordpress Post Expiration with Date and Time

Open index.php file of your theme and replace the existing loop with:

<?php
if (have_posts()) :
     while (have_posts()) : the_post();
         $expirationtime = get_post_custom_values('expiration');
         if (is_array($expirationtime)) {
             $expirestring = implode($expirationtime);
         }

         $secondsbetween = strtotime($expirestring)-time();
         if ( $secondsbetween > 0 ) {
             // Enter your post display code after that.
             the_title();
             the_excerpt();
             // Post display code ends here.
         }
     endwhile;
endif;
?>

Now while creating a post to set it’s expiration date/time create a custom field with name(key) expiration and set your expiration time as value in this format mm/dd/yyyy 00:00:00.

Source: [WPRecipes]

Set Wordpress Post Expiration with Date

Open index.php file of your theme and replace the existing loop with:

<?php
if (have_posts()) :
     while (have_posts()) : the_post();
	$currentdate = date("Ymd");
	$expirationdate = get_post_custom_values('expiration');
	if (is_null($expirationdate)) {
	$expirestring = '30005050'; //MAKE UN-EXPIRING POSTS ALWAYS SHOW UP;
	} else {

	if (is_array($expirationdate)) {
	$expirestringarray = implode($expirationdate);
	}
	$expirestring = str_replace("/","",$expirestringarray);
	} //else
	if ( $expirestring > $currentdate ) {
             // Enter your post display code after that.
             the_title();
             the_excerpt();
             // Post display code ends here.
         }
     endwhile;
endif;
?>

Now while creating a post to set it’s expiration date create a custom field with name(key) expiration and set your expiration date as value in this format yyy/mm/dd.

Source: [Snipplr]