Basic license authentication system

[stuffradio]

I've setup a basic authentication system... I'm going to encode with Ioncube.

 

What would I put in the script of the authentication script, or the MySQL database to make it so users have to use those scripts to keep their script alive. Almost everything else will be visible... so they'll try and alter it so they can nullify it. Any thoughts/suggestions? This is a basic idea I have right now:

 

$host = $_SERVER['HTTP_HOST'];

$checklicensevalid = mysql_query("SELECT * FROM `license` WHERE `domain`='$host'");
$is_valid = mysql_num_rows($checklicensevalid);
if ($is_valid == 0) {
die("You're running an illegal copy of this software!");
} else {
  echo "It's legit!";
}