update the repository and install Apache.
apt-get update
apt-get install apache2
Install PHP and Apache's mod_php extension.
apt-get install php5 libapache2-mod-php5 php5-mcrypt
Install Memcache Packages
apt-get install php5-memcache memcached
Config memcache
nano /etc/memcached.conf
-l 1.1.1.1
service memcached restart
Set Memcache as PHP's Session Handler
session.save_handler = memcache
session.save_path = 'tcp://1.1.1.1:11211'
restart Apache
service apache2 reload