Monetize Android App with AdMob without using Firebase

How to monetize android app with AdMob without using Firebase ?
1. import the Google Mobile Ads SDK with gradle
  In build.gradle file : allprojects { repositories { maven { url "https://maven.google.com"}}}
  build.gradle : dependencies { implementation 'com.google.android.gms:play-services-ads:15.0.0'} 
2. Initialize MobileAds :
MobileAds.initialize(this, "YOUR_ADMOB_APP_ID");
3. To get YOUR_ADMOB_APP_ID you have to create an AdMob account and add your app : https://apps.admob.com/utm_source=internal&utm_medium=et&utm_campaign=helpcentrecontextualopt&utm_term=http://goo.gl/6Xkfcf&subid=ww-ww-et-amhelpv4
4. Select the different ad format to apply using java code :
 - Banner ad : https://developers.google.com/admob/android/banner
 - Interstitial ad : https://developers.google.com/admob/android/interstitial
 - Native ad : https://developers.google.com/admob/android/native-unified
 - Rewarded video : https://developers.google.com/admob/android/rewarded-video