I think I was adding too much work in my previous post so here is a more simple version :)
<?php
if ("".date('l jS M Y H:i:s') ."" < "".date('l jS M Y H:i:s',strtotime($row_rsMembers['MemberValidTo'])+28800) ."") { // WebAssist Show If
?>
<p>This text will only show if under the datetime stored in database is less than 8 hours of current datetime</p>
<?php
} // ("".$currentdatetime ."" < "".$storeddatetimeandeighthours ."")
?>
(above is to demonstrate only so you would need to replace with your $_POST variables :)
Chris