If you click to download the app without Google Play Store being the middleman (link: https://cryptomator.org/android/ ), whether you have paid for a license or not, the download of the APK is initiated normally.
I don’t get it, is this because you won’t be able to use the app without a license anyway, or is it intentionally distributed for free on your website, now that it became open source?
It has always been this case. But: If you open the app, it will ask you for a license key. 
Oh ok, so basically there’s 2 different versions of the app?
One from the website directly, which is downloaded for free (but only works with a license) and one from Google Play Store that works without a license (you just buy it, download and use it)?
Did I get it right?
Yes, that’s correct!
If I get the one directly from the website, what’s the updating process like? Do I have to download and re-install each update manually from the website?
(I’m asking, cause I’m suspecting an in-app implementation where the app updates itself, isn’t possible)
The app actually checks for updates regularly (which can be disabled in the settings, of course). If an update is available, you will be notified, and you can trigger the update process, which makes the update process “almost” automatic.
You mean that while I’m using the app and an available update is detected, I will then be redirected to the website to download it manually?
Thanks for all the info btw : )
See
But you can also download and install updates manually.
Oh that’s so cool, good job guys 