A purchased license of our .NET controls includes a run time royalty-free license to redistribute the controls in your own solutions. Your end users/clients will not need to purchase licenses in order to use the applications, you developed using our products, as soon as you comply with the redistribution guidelines in our end-user License Agreement. When you deploy your applications, you have to make sure that the DLL files of the Telerik controls are protected and locked, so that your clients don't have access to them. If your clients are going to update your project via using our controls in design time, this is considered as violation of our License Agreement and they will have to purchase the appropriate number of licenses for our controls.