App store shows GET, not OPEN in spite off Evernote Plus is installed in my system

[MusicWiz 14]

I am running high Sierra. In the App store Evernote Desktop shows GET, not OPEN in spite the Evernote PLUS  is in my system. Why is that? Do I download it again?

[PinkElephant 8,079]

From my experience it is better to get the client for the Mac through a direct download from the EN website.

Even when it is the same code, the version from the AppStore will always run in a sandbox mode which inhibits interaction with other apps, and can cause problems. I am on Mojave (and looking to go to Catalina soon), but I have made a full uninstall (through AppCleaner) of my client when I ran into problems, and reinstalled from the EN website. No problems since.

[MusicWiz 14]

Thanks, for the answer, that makes a lot of sense. For me unfortunately no Mojave or Catalina as many professional apps and 3rd party plugins could have issues. Some companies can not keep up with every year OS updates.