Man pages matching name memcached_last_error_message in section 3:

memcached_last_error_message.3.en	debian 10 / libmemcached-dev
memcached_last_error_message.3.en	debian 11 / libmemcached-dev
memcached_last_error_message.3.en	debian 12 / libmemcached-dev