Ok I think I have something that uses a stored datetime in a users table in the database (if thats what you would want to do since if they update content you would want to store the datetime of that content entry in the users table). (28800 is in seconds = 8 hours)
Ive used long variable names to make the below example more meaningful:
Plus I am echoing the 2 variables just for demonstration of both datetimes to compare.
Its the first time I done this sort of thing so its a little crude :)
<?php
$currentdatetime = date('l jS M Y H:i:s');
$storeddatetimeandeighthours = date('l jS M Y H:i:s',strtotime($row_rsMembers['MemberValidTo'])+28800);
?>
<?php echo $currentdatetime; ?>
<BR>
<?php echo $storeddatetimeandeighthours; ?>
<p> </p>
<?php
if ("".$currentdatetime ."" < "".$storeddatetimeandeighthours ."") { // WebAssist Show If
?>
<p>This text will only show if under the datetime stored in database is less than 8 hours of current datetime</p>
<?php
} // ("".$currentdatetime ."" < "".$storeddatetimeandeighthours ."")
?>