https://github.com/googleads/googleads-mobile-plugins/releases - plugin for Unity3d

Android Setup

  1. Add the google-play-services_lib folder, located at ANDROID_SDK_LOCATION/extras/google/google_play_services/libproject, into the Plugins/Android folder of your project.
  2. [For users running a version of Unity earlier than 5.0] Navigate to Temp/StagingArea of your project directory and copy AndroidManifest.xml to Assets/Plugins/Android. Add the following <meta-data> tag to the AndroidManifest.xml file:

    <activity android:name="com.unity3d.player.UnityPlayerActivity" ...>
      ...
      <meta-data android:name="unityplayer.ForwardNativeEventsToDalvik" android:value="true" />
    </activity>

Whole info - https://github.com/googleads/googleads-mobile-plugins/tree/master/unity

 

Code sample:

private InterstitialAd interstitialAd = null;
private void Awake()
{
DontDestroyOnLoad(gameObject);
interstitialAd = new InterstitialAd("ca-app-pub-7595567840778202/4063720371"); //ad unit id
LoadInterstitialAd();
interstitialAd.AdClosing += OnAdClosing;
}
private void OnAdClosing(object sender, EventArgs eventArgs) //After ad has been closed you need to reload it to show one more time
{
LoadInterstitialAd();
}
public void LoadInterstitialAd()
{
if (!interstitialAd.IsLoaded())
{
var request = new AdRequest.Builder().Build();
interstitialAd.LoadAd(request);
}
}
public void ShowInterstitial()
{
if (interstitialAd.IsLoaded())
interstitialAd.Show();

To use it you need to create an account https://www.google.com/admob/

Then create a new "application" by pressing red button "+ Monetise new app".

Banner - small ad somewhere on the screen.

Interstitial - a full-screen ad.

In code you need to use an unit id - http://prntscr.com/88na48