Firstly, launch your Evernote on your Mac and then go to Preferences.
Simply check “Update to beta versions when available” box. Close the menu and Evernote will automatically ask you whether you want to update to Evernote 5 or not. If you don’t see the software update tab inside Preference, you are using Mac App Store version Evernote and you can’t update to the beta prior to the official public release at the moment.
If you are using Mac App Store version and you can’t wait until the official release of Evernote 5, here’s a little trick you can try to download it. First, you have to delete your Evernote Mac Appstore version. Then, go to Macupdate and download the “Older Version”.
Once you get the older version of Evernote, the software update button will appear again. Enjoy your Evernote 5 Beta version!