so basically every time i give someone access, and dont want them to have access, just send a new access key email to all those family\friend members?
No. The opposite. Sending or creating a new access key will only block access to people who connected via the old access key. They don't HAVE TO connect that way. In other words, you can connect to a remote library using the authentication key, or you can connect via the IP address and port combination. So, even if you originally connected them via the access key, and that's all you provided, it is a simple matter to translate this into an IP address and connect manually. All you have to do is visit the WebRemote web page (right in the invite) and it'll
GIVE you the IP address.
In the File -> Library -> Connect to Server dialog, you can actually enter an address like: 209.222.207.12:4050 (for a server at that IP address and port). Even if you change the access key, if they happen to have manually gone in and configured it that way (extremely unlikely, I agree), they'll still be able to connect. Even if you also change the port number, they could easily port scan your computer and get in, if they have your IP address.
To
really block access, you need to change the username/password combo.
Again, though, unless you have a determined and savvy user trying to gain access to your library, this isn't likely.