Apps can import the Google Mobile Ads SDK with a Gradle dependency. Open the app-level build.gradle file for your app, and look for a "dependencies" section.

dependencies {
    compile fileTree
(dir: 'libs', include: ['*.jar'])
    compile
'com.android.support:appcompat-v7:25.3.1'
   
compile 'com.google.android.gms:play-services-ads:11.0.0'
}