When using the RESTful Engine with an expired license the application throws a 500 with an unhandled exception. I would suggest you improve your application by catching your exceptions and throwing meaningful error codes and messages to the client.

I get the exception when calling the version endpoint with an expired license. I tried uploading the Postman response but that doesn't work either. Below is the stack trace.
[LicenseException: Expired license key ]
net.windward.xmlreport.ProcessReport._init(Boolean ) +6115
net.windward.xmlreport.ProcessReport.init() +26
net.windward.api.csharp.Report.Init() +24
RESTfulEngine.WebApiApplication.InitLicenseAndEngine() in C:\agent_work\1\s\restfulengine\RESTfulEngine\Global.asax.cs:87

[HttpException (0x80004005): Expired license key ]
System.Web.HttpApplicationFactory.EnsureAppStartCalledForIntegratedMode(HttpContext context, HttpApplication app) +520
System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr appContext, HttpContext context, MethodInfo[] handlers) +176
System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +165
System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +267
System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +341

[HttpException (0x80004005): Expired license key ]
System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +523
System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +107
System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +688