i have done things similar to what you are wanting.
place in your SQL table with your items the date of the access or information the date of input such as 62603 (6/26/03)
$str1 = 62403 + 200;
$str2 = date("mdy");
if ($str2 >= $str1) {
echo "Your time has expired";
} else {
echo "Do something here";
}