Wait for finish of queryProductDetailsAsync to display price of InApp product

I want to display on android button price of my InnApp product. I use queryProductDetailsAsync to get price. Issue is that when I assign price in button "binding.ButtonBuy.text = price" sometimes it don't show anything or wrong data. I suspect that its because queryProductDetailsAsync is Async and I should firstly wait for function to finish and than assing proper price. I wonder why Timber.tag("Mik").d("\nPrice: " + price) is always displaying proper price but when assign to button its not always proper. Can somebody help me to modify code properly to wait with "binding.ButtonBuy.text = price" when price is ready ?

class Zakupy : AppCompatActivity(), PurchasesUpdatedListener {

    private lateinit var binding: ActivityZakupyBinding
    private lateinit var billingClient: BillingClient
    private var price: String = "?"    

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    binding = ActivityZakupyBinding.inflate(layoutInflater)
    setContentView(binding.root)
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);


    billingClient = BillingClient.newBuilder(this).enablePendingPurchases().setListener(this).build()

    billingClient.startConnection(object : BillingClientStateListener {
        override fun onBillingSetupFinished(billingResult: BillingResult) {
            if (billingResult.responseCode == BillingClient.BillingResponseCode.OK) {
                Timber.tag("Mik").d("BillingRespondCode-OK")

                val productList = QueryProductDetailsParams.newBuilder().setProductList(ImmutableList.of(QueryProductDetailsParams.Product.newBuilder().setProductId("add_free").setProductType(BillingClient.ProductType.INAPP).build())).build()


                billingClient.queryProductDetailsAsync(productList) { billingResult,
                                                                      productDetailsList ->

                    val productDetails = productDetailsList[0]  // choose index zero because we had only 1 product
                    
                    price = productDetails.oneTimePurchaseOfferDetails?.formattedPrice.toString()
                        .filter { it.isDigit() || it == ',' || it == '.' } + " " + productDetails.oneTimePurchaseOfferDetails?.priceCurrencyCode

                    Timber.tag("Mik").d("\ncena: " + price)
                    binding.ButtonKup.text = price
                }