Login to cPanel and select the "Memcached Manager by SuperHosting" menu.
In the next window you can see the status of Memcached.
Choose the memory size (from the hosting account's memory) which will be allocated for Memcached. Click on the "Save and Enable" button.
All changes will take effect within 5 minutes after saving.
For a host name you need to use 127.0.0.1.
Please keep in mind that if Memcached is deactivated and then reactivated, the port will change.
This means that you need also to update it in the website settings.