flash (macromedia):

if you have the swf in an html do this in the head:<br>
<script>
go_to = "http://www.yoursite.com/page_after_swf.htm";
num_days = 15;
function ged(noDays){
var today = new Date();
var expr = new Date(today.getTime() + noDays*24*60*60*1000);
return expr.toGMTString();
}

function readCookie(cookieName){
var start = document.cookie.indexOf(cookieName);
if (start == -1){
document.cookie = "seenit=yes; expires=" + ged(num_days);
} else {
window.location = go_to;
}
}

readCookie("seenit");
// -->
</script>