This seems to be a bug in the Mac App Store. It looks like the the Mac App Store has not got the complete list of all your past purchases. It may resolve itself after a day or two but there is something you can do in the meantime to force the list of apps you have already purchased to update:
If you click your account name at the bottom left of the Mac App Store screen, you will see your past purchases (and Just Press Records will be missing). If you hover your mouse over any app you should see a button appear with three dots. Press this and a menu will appear. From this menu, select 'Hide Purchase...' (we would recommend doing this on an app you don't care about if possible - although it can be unhidden later) then confirm you want to hide this app. At this point, your list of purchased apps will refresh and Just Press Record should appear.
To unhide the app you just hid, press 'Account Settings' at the top of your account page then look for the 'Hidden Items' section - there should be a 'Manage' button where you can unhide the app.