Updating limitation based on subscription types

Author: yutanglin16

articles/app-service/manage-custom-dns-buy-domain.md

@@ -17,6 +17,11 @@ App Service domains are custom domains that are managed directly in Azure. They
 * To use an App Service domain, the app's [App Service plan](overview-hosting-plans.md) must be a paid tier and not **Free (F1)**. See [Scale up an app](manage-scale-up.md#scale-up-your-pricing-tier) to update the tier.
 * [Remove the spending limit on your subscription](../cost-management-billing/manage/spending-limit.md#remove).
 
+> [!NOTE]
+> Some subscriptions types would be required to have sufficient history on Azure prior to creating an App Service Domain.
+> Free trial and credit based subscriptions are not eligible to create an App Service Domain.
+>
+
 ## Buy and map an App Service domain
 
 For pricing information on App Service domains, visit the [App Service Pricing page](https://azure.microsoft.com/pricing/details/app-service/windows/) and scroll down to App Service Domain.
@@ -71,7 +76,6 @@ For pricing information on App Service domains, visit the [App Service Pricing p
     > [!NOTE]
     > App Service Domains use GoDaddy for domain registration and Azure DNS to host the domains. In addition to the yearly domain registration fee, usage charges for Azure DNS apply. For information, see [Azure DNS Pricing](https://azure.microsoft.com/pricing/details/dns/).
     >
-    >
 
 1. When the domain registration is complete, you see a **Go to resource** button. Select it to see its management page.
 
@@ -80,7 +84,9 @@ For pricing information on App Service domains, visit the [App Service Pricing p
 You're now ready to assign an App Service app to this custom domain.
 
 > [!NOTE]
-> Depending on the subscription type, a sufficient payment history within Azure may be required prior to creating an App Service domain. 
+> Some subscriptions types would be required to have sufficient history on Azure prior to creating an App Service Domain.
+> Free trial and credit based subscriptions are not eligible to create an App Service Domain.
+>
 
 ## Map a hostname manually