If you have the Reports ForNAV Converter or the Reports ForNAV Designer installed on your client, just open one of them and choose either Help or Settings and About:
If you are running the reports only (and do not have our tools installed on any client) – you have to go to the service tier and find the add-ins folder under the Dynamics NAV folder. In the ReportsForNAV folder you find the DLL. If you right click on the DLL, you will see Properties and the version number under Details:
