Try clicking "tools" > "license product"

I tried that, still getting an error message. It's weird, it had been working fine until this afternoon. And support is closed today due to MLK. 

See if this helps:

Resolving error code AUF10 unable to license ProSe... - Intuit Accountants Community

That's all correct. It's weird because it stopped working from one minute to the next. I guess I'll just have to wait until tomorrow to contact support. Thanks for your help!