256MB is the max limit and when not in use linux will just swap it out. As for the logs in the big scheme of things, 50MB is not much.
That is not to say this is not a problem. @crazybrad what kind of log messages are you seeing? It's the nature of the internet that publicly exposed services can be accessed. The TURN server is public and has to be. Do you have a firewall? It's easiest to just block it there if it bothers you. The ports to block are:
TURN_PORT: 3478, // tcp and udp
TURN_TLS_PORT: 5349, // tcp and udp
TURN_UDP_PORT_START: 50000,
TURN_UDP_PORT_END: 50100,