Hi Ethan,
There is a single instance of memcache per data center we run. self.cache.set will have it's cache key scopped to your SDK service. If you set an entry with a key of name and value of Ethan for one online user, another online user will also see that same value.
If you want this to be scopped to a single session then opt to use self.session_cache.set instead. This will construct a key that's unique that just that session without any overlap between two users.