I think what smiley means is that when you are a subscriber, there is (or was when I was a subscriber) a bug that when you click on "Update Now", the models.lst get corrupted and you end up with just a handful of cards in your collection.
But do not worry, while this is kinda irritating, you can get your collection back by either backing up the models.lst file or clicking "Update Now" again. Rest assured you will not lose anything on your hard drive.
Has not happened to me since my subscription ended so I guess it only affects subscribers.