To implement 'Remember Me' functionality in cakephp, you need to follow following steps.

Step1 :  Add the following code in app/Config/core.php

Configure::write('Session', array(
		'defaults' => 'php'
		'defaults' => 'php',
		'cookieTimeout' => 0
 	));

Step2 : Add the following code in app/Controller/AppController.php

 public function beforeFilter() {

        $this->Auth->allow('login', 'logout','forgot','register','getCities','getStates','getData');
        $this->Auth->loginRedirect = array('controller' => 'users', 'action' => 'home');
        $this->Auth->logoutRedirect = array('controller' => 'users', 'action' => 'logout', 'login');
        // $this->Auth->authorize = array('Controller');
        $this->Auth->redirectUrl(array('controller' => 'users', 'action' => 'home'));
        $this->Auth->authenticate = array(
            'Cookie' => array(
                'fields' => array(
                     'username' => 'email',
                     'password' => 'password'
                ),
                'userModel' => 'User',
            ),
            'Form' =>array(
                    'passwordHasher' => 'Blowfish',
                    'fields' => array('username' => 'email')
                    ),

            
        );
        $this->Cookie->type('rijndael');
        $this->set('authUser', $this->Auth->user());

        @$cookieData = $this->Cookie->read('User');
         // echo debug($cookieData);
        if (!empty(@$cookieData))
        {   


            $this->request->data["User"]["email"] = $cookieData["User"]["email"];
            $this->request->data["User"]["password"] = $cookieData["User"]["password"];
        }

    }

 Step3 : Add the following code in app/Controller/Component/Auth/CookieAuthenticate.php

<?php
App::uses('BaseAuthenticate', 'Controller/Component/Auth');
App::uses('AuthComponent', 'Controller/Component');
App::uses('Router', 'Routing');

/**
 * An authentication adapter for AuthComponent.  Provides the ability to authenticate using COOKIE
 *
 * {{{
 *  $this->Auth->authenticate = array(
 *      'Authenticate.Cookie' => array(
 *          'fields' => array(
 *              'username' => 'username',
 *              'password' => 'password'
 *          ),
 *          'userModel' => 'User',
 *          'scope' => array('User.active' => 1),
 *          'crypt' => 'rijndael', // Defaults to rijndael(safest), optionally set to 'cipher' if required
 *          'cookie' => array(
 *              'name' => 'RememberMe',
 *              'time' => '+2 weeks',
 *          )
 *      )
 *  )
 * }}}
 *
 */
class CookieAuthenticate extends BaseAuthenticate {

    public function __construct(ComponentCollection $collection, $settings) {
        $this->settings['cookie'] = array(
            'name' => 'RememberMe',
            'time' => '+2 weeks',
            'base' => Router::getRequest()->base
        );
        $this->settings['crypt'] = 'rijndael';
        parent::__construct($collection, $settings);
    }

/**
 * Authenticates the identity contained in the cookie.  Will use the `settings.userModel`, and `settings.fields`
 * to find COOKIE data that is used to find a matching record in the `settings.userModel`.  Will return false if
 * there is no cookie data, either username or password is missing, of if the scope conditions have not been met.
 *
 * @param CakeRequest $request The unused request object
 * @return mixed False on login failure. An array of User data on success.
 * @throws CakeException
 */
    public function getUser(CakeRequest $request) {
        if (!isset($this->_Collection->Cookie) || !$this->_Collection->Cookie instanceof CookieComponent) {
            throw new CakeException('CookieComponent is not loaded');
        }

        $this->_Collection->Cookie->type($this->settings['crypt']);
        list(, $model) = pluginSplit($this->settings['userModel']);

        $data = $this->_Collection->Cookie->read($model);
        if (empty($data)) {
            return false;
        }

        extract($this->settings['fields']);
        if (empty($data[$username]) || empty($data[$password])) {
            return false;
        }

        $user = $this->_findUser($data[$username], $data[$password]);
        if ($user) {
            $this->_Collection->Session->write(AuthComponent::$sessionKey, $user);
            return $user;
        }
        return false;
   }

    public function authenticate(CakeRequest $request, CakeResponse $response) {
        return $this->getUser($request);
    }

    public function logout($user) {
        $this->_Collection->Cookie->destroy();
    }

} 

Step4 : Add the following code in app/Controller/UsersController.php

public function login()
	{
		if($this->Auth->user()){
			$this->redirect(array('controller'=>'Users','action'=>'home'));
		}
		if ($this->request->is('post')) {
			


			if ($this->Auth->login()) {
				$this->_setCookie($this->Auth->user('id'));
				$this->redirect($this->Auth->redirect());
			} else {
				$this->Session->setFlash(' Invalid username or password ');
			}
		}
		
		if ($this->Auth->loggedIn() || $this->Auth->login()) {
			return $this->redirect($this->Auth->redirectUrl());
		}
	}


   protected function _setCookie($id) {


		if (!$this->request->data['remember_me']) {
			return false;
		}

		$data = array(
			'User' => array(
				'email' => $this->request->data['User']['email'],
				'password' => $this->request->data['User']['password']
				));
		
		$this->Cookie->write('User', $data, true, '+2 week');
		return true;
	}

Step5 : Add the following code in app/View/Users/login.ctp

<?php echo $this->Form->create('User'); ?>
 	<fieldset>
 		<legend><?php echo __('Please enter your username and password'); ?></legend>
		<?php echo $this->Form->input('username');
		echo $this->Form->input('password');
	?>
		<?php
			echo $this->Form->input('username');
			echo $this->Form->input('password');
			echo $this->Form->checkbox('remember_me');
		?>
 	</fieldset>
 <?php echo $this->Form->end(__('Login')); ?>
 </div>