dAGGER: Yes, as long as you are on a team in a fellowship, and are in the tournament when it starts up, you will continue on until the end of the tournament, regardless of your membership level.

Also, right now is a good time to join. I believe the "Christmas action" is still going on. Depending on the color circle that appears, you can get extra time, up to 100%, if you do it at the right time. (Keep checking back until the best color is there)

EDIT: Oh, this extra bonus only applies for purchases of a year, sorry.