The keynote speaker is an important person or an influential person of a Congress. It is often someone who has the necessary expertise or experience on the subject of Congress. It is a person who takes the welcome note, often also announces the other speakers and talks to the other parts of the Congress or event.
A FUP often applies when using an Internet connection. You may download it, but it should not be done constantly so that other users are bothered by it: it is therefore not allowed to be extremely much data user. What happens when the FUP is violated varies by contract, it may be that no data traffic is possible at all, or that an additional account is coming. Because Fair Use is rather opaque, you don't know as a user when you are violating it.