licensing terms and term definitions

Where does one find the definition of terms: seat, session and device?

Some more specific questions (pertaining to licensing under Single User license and the terms):

1. Is session equivalent to an estabilished connection between two devices running teamviewer? (That would mean only a one concurrent connection)
2. In case that device (in the above sense) means the computers under which teamviewer can be installed and from which the connection to clients can be initiated, how does one solve obvious problems such as connecting from rented computers (3 devices is an extremely strict limit in today world: a work computer, a personnal laptop, a phone and a tablet and this is 4, what if i am somewhere and use someone's computer?