If there is a proxy configured on your environment you may get this error when trying to activate the License: ActivationFailed: The remote name could not be resolved

To fix the issue you can specify the proxy settings in the web.config? You can find the example of configuration here: http://www.karthikscorner.com/sharepoint/configure-proxy-server-sharepoint/

If your proxy requires authentication, you can share the access with your Application Pool account and add useDefaultCredentials="true" to configuration. More information on this here: https://stackoverflow.com/a/875700/246719