What is the version of Cookies Toolkit that you are working with? It seems that you have an older versions code on the page that is not taking into account the expiration days. You should update the function on this page on lines 7-13 with this:
<script type="text/javascript">
<!--
function WA_setFormCookie(cookieObj, formObj, cookieName, expdays) {
if (expdays) {
cookieObj.expires = daysToExpire(expdays);
}
else {
cookieObj.expires = "";
}
cookieFormToString(cookieObj,formObj,cookieName);
}
//-->
</script>
This should not be an issue in the latest release of the cookies toolkit which is 3.1.2 at the time of this post.