King want players to pay gold for the 5 extra moves to keep going. Ads disappear from time to time when King decide to test out if more players will spend money on the game. Any one who does spend money on the game is likely to lose free ads as soon as they do.
Don't spend money on the game. It's such a waste of money and will only encourage King to keep doing this. Which level are you stuck on? Maybe we can help with some tips.