Hello Nima,
What would you like to do exactly? Would you like to call a function to access memcache? Cloud Functions are ephemeral, spinning up on-demand and back down in response to events in the environment. By contrast, if you want to use memcache effectively, you need to call it at least twice: to store something and to retrieved what had been stored.
There is a Memcache API, which provides memcached-alike API to application developers to store data in memory when reliable storage via the DataStore API isn’t required and higher performance is desired. You may get more insight by reading the "google.appengine.api.memcache package" documentation
page.