Not Need memcache...
enough memcached!
Log in to PrestaShop as the administrator.
On the menu bar, click ADVANCED PARAMETERS, and then click Performance.
Scroll down the page to the CACHING section.
Under Use cache, click YES.
Under Caching system, select Memcached.
Click Add server. Additional settings appear.
In the IP Address text box, type 127.0.0.1.
In the Port text box, type 11211.
In the Weight text box, type 1.
Click Add Server.
Click Save.