Admob code question

I just finished my first game and I’m trying to practice how to put admobs in it. I just want to make sure that I don’t call it multiple times with my code because I read that I might get in trouble for that.

Here’s my code:

void Start () {
	admob = GetComponent<AdMobPlugin>();
	admob.CreateBanner(AD_UNIT_ID, AdMobPlugin.AdSize.SMART_BANNER, false, "", false);
	admob.RequestAd();
	admob.ShowBanner();

}

// Update is called once per frame
void Update () {

	if (Application.loadedLevelName == "Stage")
	{
		if (!hidden)
		{
			admob.HideBanner();
			hidden = true;
		}
	}
	else if (Application.loadedLevelName != "Stage")
	{
		if (hidden)
		{
			admob.ShowBanner();
			hidden = false;
		}
	}
}

Nothing wrong with it, it won’t get you in trouble.