Me too, I recently had to do redo my phone app for this season – somehow No-Ip “lost” track after 8 months of non-use. In studying what i needed to do, i happened to learn that WU at some point re-instated their free api keys for folks that submit their own WX data. I got my new key and thus had the same question as you posted.
I look forward to an official reply, but it looked like they removed the WU key option from the app after this thread got started. Not sure if there is any work being done to put the WU key back in – now that WU folks resumed the free service once again….
Running App 1.8.5, Firmware 2.1.8 (1) 3.0 AC