lib_unity_purchase/Documentation~/UnityIAPModuleRegistration.md

Registering your store

Call the RegisterStore method supplying a name for your store and your implementation, which must implement the IStore interface.

public override void Configure() {
    RegisterStore(“GooglePlay”, InstantiateMyStore());
}

private void InstantiateMyStore() {
    if (Application.platform == RuntimePlatform.Android) {
        return new MyAlternativeGooglePlayImplementation ();
    }
    return null;
}

The store name must match the name developers use when defining products for your store so Unity IAP uses the correct product identifiers when addressing your store.