Can I lose my rank?

Yes, but if you keep playing the way you have been playing, there is no reason to lose it. Your Captain, Major and Colonel Rank lasts until the end of the calendar month that follows the month in which you qualified. For example, if you have earned 3,000 RPs from May 1st through May 20th, you will achieve Major Status for June. Your status will last until the end of June. If you have earned enough Rank Points in June, you will keep your status. Or if you have earned enough Rank Points for the next status, we will move you up a rank.