Add pricing switch instructions

Author: andreamichaelmsft

articles/virtual-network-manager/overview.md

@@ -45,6 +45,16 @@ For current information on the regions where Azure Virtual Network Manager is av
 
 ## Pricing   
 For pricing details, see [Azure Virtual Network Manager pricing](https://azure.microsoft.com/pricing/details/virtual-network-manager/).
+
+New Azure Virtual Network Manager instances will charge solely on the virtual network-based pricing described in the pricing page above.
+
+Azure Virtual Network Manager instances created prior to the release of the virtual network-based pricing will continue to charge on the subscription-based pricing described in the pricing page above. If you prefer for your Azure Virtual Network Manager instance to instead charge on the virtual network-based pricing, follow the steps below to switch its pricing model.
+
+1. In the Azure Portal, search for "Preview features".
+2. On the "Preview Features" page, ensure the subscription selected is the subscription that contains your Azure Virtual Network Manager instance. Filter the features by "Network manager".
+3. Select the feature named "Network manager billing by virtual networks" and register. The Azure Virtual Network Manager instance in the registered subscription will now charge on the virtual network-based pricing.
+
+:::image type="content" source="./media/overview/new-pricing-feature-flag-registration.png" alt-text="Screenshot of Preview Features page with Network manager billing by virtual networks feature selected.":::
 
 ## FAQs  
 For FAQs, see [Azure Virtual Network Manager FAQs](faq.md).