[Answer]-Python/Django Memcached keys expiration

Checkout Memcached’s wiki article NewUserInternals – No Guts No Glory. An item that expires will continue to set in memory until one of the following happens:

• Client will attempt to fetch expired data. Memcached will see that it’s expired, reclaim the memory, and not return the value to the client.
• When a client request to store a new item, Memcached will check against Least Recently Used (LRU) for any expired items, and reclaim the memory.