AudioSource.loop

Is the audio clip looping?

If you disable looping on a playing AudioSource the sound will stop after the end of the current loop.

JavaScript

// Stop looping the sound
audio.loop = false;

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Example() {
        audio.loop = false;
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Example():
        audio.loop = false