Addwyn

That may explain why my KS16 can now be set to 30 km/h without any unlock code...

Finally, YOU'r right and I'm totally wrong ! A few minutes ago, I totally cleared my Kingsong's app memory and restarted the app. Then, despite my KS16 is 1057 km, it was impossible to set a max speed above 20 km/h (witch is the factory default). BUT if I close the phone app and start it again, then it's possible to set a 30 km/h max speed (without any unclock code) !!! So, the app is not unlocked (the "Speed limit decoding" menu item still asks for the unlock code) but the max speed can still be set to 30 km/h !!! So, you're right, it seems that the WHEEL is unlocked (and maybe the app need to be connected twice to "know" that the wheel is unlocked)... Weird behavior !

I've never heard about an automatic unlocking after a certain mileage and that's not mentioned in the KS16's user guide.

Yes ! That's very easy because the unlock code does not unlock the wheel but it only unlocks the phone's app ! Therefore, you just have to install a clean new app on your phone (and set the max speed of your used wheel to anything under 25 km/h) to be back in factory's initial state... Your "locked" phone's app will not allow you to set a max speed above 25 km/h anymore. Thus, you respect your laws !

Some other pics there (if you don't understand French, Google translator will be your friend ) https://www.espritroue.fr/topic/668-kingsong-ks16b-vue-de-lintérieur/