Upon opening RivEX you are told that it has been unable to locate the RivEX license file.
The RivEX license file (RivEX_License.rlf) is not in the expected folder location (C:\RivEX\License). It has been either deleted by mistake, not placed here during the installation process or most likely you have installed RivEX in a folder and not at the root of C:\ drive. The correct location is shown here. Reinstall RivEX at the correct location, remember to remove the link to the incorrect Bin folder within the AddIn manager.