If the .NET OPC UA application cannot be licensed as described in Licensing the SDK, check the following steps:

Do You Use the Correct Assemblies?

Check the Product Version of UnifiedAutomation.UaBase.dll in the “bin” folder of your application. If the Product Version contains the string “_EVAL”, then you are not using the correct assemblies. Use the Release Version of the assemblies instead.

Do You Use the Correct License File?

Check if the license file used in your application is binary equal to the license file you retrieved from your download share (WebDAV or ftp).

Do You Invoke the Commands in the Correct Order?

ApplicationLicenseManager.AddProcessLicenses must be called before ApplicationInstance.Start is called.

Do You Use the Correct License Type?

If the OPC UA application is a server application, you need a UaSdkNetBundle license.