By default, memcached uses up to 64 MB of memory. You can set the size with the -m option from the command line:
memcached -p 11211 -u nobody -l 127.0.0.1 -m 128 -d
But after rebooting, it will return to 64 MB. The question is how to change (increase) this size so that when the system reboots it is saved?