Hello,

in Flash you need to define what you want to do, or else it wll continue playing.

You will need to put a single comman in ActionScript on the last frame, which is stop();

Open your Flash, find the LAST frame of your animation, click the frame (if you have several layers it doesn't matter which one you pick), open the actionscript panel (F9), and type in stop(); exactly like this.

Thats it.