Glassfy.initialize(this, "8NOV6FQBHHRJ4F9N2HV0HUXOQ5LL0QA3", false, null)
Glassfy.offerings { offers, error ->
    val offer = offers?.all?.find {  o -> o.offeringId == "my_offering" }
    val sku = offer?.skus?.firstOrNull() ?: return@offerings

    Glassfy.purchase(this, sku) { transaction, err ->
        transaction?.permissions
            ?.all
            ?.find { p -> p.permissionId == "premium" && p.isValid }
            ?.let {
                // unlock premium
            }
    }
}