Yeah, all you have to do to get a game added to your download list is to try to initiate the download, whether it stops with a 'disk is full' error, you cancel the download after it has started or you allow the download to complete, it will be added to your list and you can download it whenever you want regardless of whether or not it's no longer in a Plus offer. You can't, however, download or play Plus games if your membership expires.