Macau Quest will end on November 30, 69 days left. I just do not know if this promotion will end when there is a player who first reaches level 21 which is the last. There is nothing in the mechanics or in the TAC.
I barely reached level 3, it seems to me that level 21 is unrealistic.
21 is the limit of dreams, the higher the level the harder it is to go to the next, but it is very tempting.