SerialKey

function SerialKey($Length){

    $chars = '1A2B3C4D5E6F7G8H9I1J2K3K4L5M6N7O8P9Q1R2S3T4U5V6W7X8Y9Z';
    $str2 = strtolower($chars);
    $chars = $chars.$str2;
    $chars = str_split(str_shuffle($chars));
    $serial = '';
    $max = count($chars)-1;
    for($i=0;$i<$Length;$i++){
        $serial .= (!($i % 5) && $i ? '-' : '').$chars[rand(0, $max)];
    }

    return $serial;
}