To my knowledge you would only have to take another exam if you moved to a state that did not accept the regional licensing exam you took. For example, I go to UTHSCSA and I will be taking the WREB. If I decided to practice elsewhere, I wouldn't have to take another exam as long as I moved to a state that took the WREB. But if I moved to a state that only took the NERB, then I would have to take the NERB in order to practice in that state.