When using the HMS core site kit, Is it mandatory to enable billing. What if it is not enabled?.
For Enterprise developer you have to subscribe to relevant pay-as-you-go plan to use paid APIs of Site kit, else you will face error 010027 as shown in the screenshot . This options is only for enterprise developers. This parameter is not required by individual developers. FAQ question For more information about site kit pricing
For more information about general pricing and quotas refer