How to find the number of messages sent to Azure service bus topics

Hi Team, 

I am following the below article and was successfully sending the messages to the topic, but I want to keep track of the number of messages I have sent. 

https://docs.microsoft.com/en-us/azure/service-bus-messaging/service-bus-dotnet-get-started-with-queues

I have the following questions

1. I want to find the number of messages sent to my azure service bus topics, so that I can stop sending after certain limitation.
2. What is the difference between these [Microsoft.Azure.ServiceBus] and [WindowsAzure.ServiceBus]
   
3. Which dll I have to use from nuget?
4. Both dlls are having different classes?