I'd strongly recommend looking into Newtonsoft.Json:
http://james.newtonking.com/pages/json-net.aspx
NuGet: https://www.nuget.org/packages/newtonsoft.json/
After adding the reference to your project, you just include the following usingusing at the top of your file:
using Newtonsoft.Json.Linq;
And then within your method you can use:
var request= (HttpWebRequest)WebRequest.Create("www.example.com/ex.json");
var response = (HttpWebResponse)request.GetResponse();
var rawJson = new StreamReader(response.GetResponseStream()).ReadToEnd();
var json = JObject.Parse(rawJson); //Turns your raw string into a key value lookup
string licsene_valuelicense_value = json["licencse"]json["license"].ToObject<string>();