If you got bellow error when use memcached in Laravel, please check following steps.

exception 'Symfony\Component\Debug\Exception\FatalErrorException' with message 'Class 'Memcached' not found' in /var/www/gw/vendor/laravel/framework/src/Illuminate/Cache/MemcachedConnector.php:51

Install memcached

$ sudo apt-get install php5-memcached memcached

Enabled php5-memcached

sudo php5enmod memcached

Restart apache web server

$ sudo service apache2 restart

Check memcached service status

$ sudo service memcached status

* memcached is running

Clear cache

$ php artisan cache:clear