This is hard to believe, but some people are desperate as to keep registering accounts to level up their adoptables.  Let's make this method of leveling up not worth it.
Step 1:
Run this query
	PHP Code:
	
		
			
ALTER TABLE users ADD (ip VARCHAR(30) NOT NULL DEFAULT "0") 
		
	
 Step 2:
Open register2.php
Find 
	PHP Code:
	
		
			
// Connect to our database 
		
	
 Above this line, put
	PHP Code:
	
		
			
$ip = $_SERVER['REMOTE_ADDR']; 
$ip = preg_replace("/[^a-zA-Z0-9@._-]/", "", $ip); 
		
	
 Step 3:
Still in register2.php, find this code:
	PHP Code:
	
		
			
//Check that username does not already exist
$query = "SELECT * FROM users WHERE username = '$username'";
$result = @mysql_query($query);
$num = @mysql_numrows($result);
//Loop out code
$i=0;
while ($i < 1) {
$luser=@mysql_result($result,$i,"username");
$i++;
}
$luser = strtolower($luser);
$u2 = $str = strtolower($username);
if($luser == $u2){
$template = replace(':ARTICLETITLE:','Error',$template);
$template = replace(':ARTICLECONTENT:','Your username has been taken.  Please <a href="register.php">go back</a> and select a different username.',$template);
echo $template;
die();
} 
		
	
 
Below all of that, put
	PHP Code:
	
		
			
// Check that user is not making multiple accounts
$query = "SELECT * FROM users WHERE ip = '$ip'";
$result = @mysql_query($query);
$num = @mysql_numrows($result);
//Loop out code
$i=0;
while ($i < 1) {
$ip2=@mysql_result($result,$i,"ip");
$i++;
}
if($ip == $ip2){
$template = replace(':ARTICLETITLE:','Error',$template);
$template = replace(':ARTICLECONTENT:','You are not allowed to make multiple accounts.',$template);
echo $template;
die();
} 
		
	
 Step 4:
Find this line
	PHP Code:
	
		
			
//All checks pass, create the user 
		
	
 Insert below it:
	PHP Code:
	
		
			
$pass1 = md5($pass1); //MD5 the password
mysql_query("INSERT INTO users VALUES ('', '$username', '$pass1','$email','free', '$ip')"); 
		
	
 Note: if you have installed my currency mod, you'll want to insert this instead:
	PHP Code:
	
		
			
$pass1 = md5($pass1); //MD5 the password
mysql_query("INSERT INTO users VALUES ('', '$username', '$pass1','$email','free', '0', '$ip')");