BluBrd how the new google play account will know which apps to update
It will look at the installed apps, see which ones are available in Play Store, and update them when necessary. It doesn't need to keep a list, because it can see what apps you have.
It might be able to tell that they were previously installed from your old account though, so you might want to uninstall them for that reason. There may also be other ways of linking the old and new accounts.