Deploying an application that uses the Telerik® UI for ASP.NET Ajax controls is done in the same manner any other ASP.NET WebForms application is deployed.
To ensure a successful deployment, you need to check the following items:
For the controls to be recognized by the server, the application must properly reference the Telerik.Web.UI.dll assembly.The Included Assemblies help article explains where you can find the file(s) that you need.
Make sure that the needed assemblies are copied over to the production server. This often involves setting the CopyLocal property of the WebApplication reference to true. In case you are deploying the assemblies in the GAC, examine the Working with Assemblies in the GAC article.
Make sure that the needed additions are made to the web.config on the production server. The web.config Settings Overview article lists them.
Make sure that the .NET 4.xx+ is installed on the server.