You can promote your Android app using Google AdWords which has the Google service.
Google AdWords has 3 different options for promotion.
1.Universal App Campaigns
You should allow AdWords to generate a variety of automatically promoted ads for your app that will appear on the Search Network, the Display Network, and the YouTube Network.
- Ads are created for you using the creative text you enter, as well as the details provided for your app in the Google Play Store (such as your icon and images). These ads can run on all available networks.
- Include an optional YouTube video link for your ads so that they can be viewed on YouTube.
For more information, read Creating an App Campaign article.
2.Mobile App Downloads
In order to download users to your app, increase the number of app downloads with ads that lead directly to the app store.
- Available on Search Network, Google Display Network, and YouTube.
- Ad formats include app installation standard, image, and video ads.
For more information, please read the relevant article Creating an App Campaign.
3.Mobile App Interaction
Re-interact with your existing users with ads that deeply link to specific screens in your mobile app.
- Available for Search Network and Google Display Network campaigns.
- Ad formats app interaction includes standard and image ads.
For more information, please read the relevant article Creating an App Campaign.