This is work and simple solution.
last lines look now that in my file:
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation fileTree(dir: 'src/main/libs', include: ['*.jar'])
// note Gradle will use newest version if multiple specified
implementation('androidx.appcompat:appcompat:1.2.0')
implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'
annotationProcessor 'androidx.lifecycle:lifecycle-compiler:2.6.1'
def billing_version = "6.1.0"
implementation "com.android.billingclient:billing:$billing_version"
}