Qualification accounts are billed every 30 calendar days. Funded accounts have a one-time activation fee but no recurring costs. However, during the first full calendar month and thereafter, make sure to place a trade on at least 5 separate trading days per calendar month to avoid an inactivity fee of $79. This inactivity fee will be reassessed each calendar month.
Note that resets do not restart the date for the billing cycle on qualifications. It may make more sense to simply start a new account rather than resetting if you have a limited number of days before the next billing. If you are disqualified from the qualification and have 10 trading days or less before the next monthly billing, you should simply cancel the account and start a new one rather than resetting.