Easy. You have a bunch of stuff in a Timeline, but only want to export one of those elements. Assign it a unique Role, then when you Export (Cmd-E) set to export roles as separate files. Then you can specify only exporting that one role by itself. Check out this mini-tutorial for more information.
Then you are probably up to date. If note, move the Motion 5 application from the Application folder to the Trash, but do not empty the trash. Launch the App Store, go to the Purchased tab, click Install button to the right of the Motion 5 listing.