You've been there, you have a great App running but you're no near to have a valid Business Model.
Your Free Tier is running out and you're in fear of going out of business.

Well, AdMob for iOS is now covered for React Native too, thanks to this wrapper from Melih Mucuk. Good Luck!

react-native-admob-sample on GitHub

var BannerAdUnitId = "BannerAdUnitID";
var InterstitialAdUnitId = "InterstitialAdUnitID";

var AdMob = require("NativeModules").AdMobManager;

AdMob.loadInterstitial(InterstitialAdUnitId);
// for showing Interstitial Ad
AdMob.showInterstitial();

// for showing Banner Ad
AdMob.showBannerOnBottomOfTheView(BannerAdUnitId);