For example https://chocolatey.org/packages/winrar.
It simply installs the trial version of WinRAR, into which you can then insert your serial number or file. From then on it uses the update mechanism to always write over the existing installation. But your license is still there. Just as if you were downloading the installer from the website and running it.
I think if Affinty's update behavior is the same, it could just as easily work. Someone has to maintain the packages.