"The first time you log in, while connected, the system caches your login credentials on the computer.  After this has occurred, you will no longer need to be connected to the internet to log in.  The computer can be taken from client to client allowing you to log in each time you need to access the program, without requiring the internet.  Once your password expires, you will need to be connected to update it, which will allow the system to cache the authentication locally once again. (This is not your browser cache)."
https://accountants-community.intuit.com/articles/1860482-internet-connection-required-message-when-...