Just Press Record for Apple Watch, iOS, & Mac
Just Press Record is one of those apps that is both aptly named and awesome in its simplicity. Open it on just about any Apple device (iPhone, iPad, Apple Watch, or Mac), press the big red button to record, press it again when you're done. That's it. (Dick Tracy would love this app.)
Rename the file if you like, then watch as it instantly syncs to any and all other Apple devices you own via iCloud Drive. These .m4a recordings are organized by date and time, and can be shared to other apps and services.
The implications of Just Press Record are huge — musicians and journalists et al will obviously find such an app useful, or perhaps a music/dance teacher sending feedback to a student, but imagine recording a podcast from your watch. Concerns about audio quality aside, that's pretty cool. I can also see how this could help an innocent citizen present covert proof of abuse of authority (Disclaimer: I am not a lawyer, only theorizing), or on the brighter side, a parent capture a funny conversation with their child.
Get the iOS/watchOS version for $3 on the App Store. The Mac version, which has been around as a standalone app from April 2015 until now, is $5.