How to access Session in Web API MVC 5

"code.msdn.microsoft.com/How-to-create-and-access-447ada98"
"stackoverflow.com/questions/14138872/how-to-use-sessions-in-an-asp-net-mvc-4-application"

protected void Application_PostAuthorizeRequest()
    {
        if (IsWebApiRequest())
        {
            HttpContext.Current.SetSessionStateBehavior(SessionStateBehavior.Required);
        }
    }

    private bool IsWebApiRequest()
    {
        return HttpContext.Current.Request.AppRelativeCurrentExecutionFilePath.StartsWith(WebApiConfig.UrlPrefixRelative);
    }