// Edit file android/build.gradle
buildscript {
    ext {
        buildToolsVersion = "29.0.2"
        minSdkVersion = 21 //min version must not be below 21
        compileSdkVersion = 29
        targetSdkVersion = 29
    }
}
​
allprojects {
    repositories {
        mavenCentral()
    }
}
​
-------
//Edit file android/app/build.gradle
dependencies {
    //Add this line to integrate Google Play Billing
    implementation 'io.purchasely:google-play:2.5.0'
}