$token = md5(uniqid());



<form method="POST">
    <h2>Register</h2>
    <input type="text" name="username" placeholder="Username" required><br><br>
    <input type="password" name="password" placeholder="Password" required><br><br>
    <button name="register">Register</button>
</form>


$conn->query("INSERT INTO users (username, password, token) 
VALUES ('$user', '$pass', '$token')");

<p>If you registered successfully, Login here <a href="index.php">Login here</a></p>