It is my understanding that as long as you keep your Auctiva account and your Auctiva Token is not disabled..the scrolling gallery will still appear in your listings as long as you do not change it in your Auctiva Preferences/Settings.
(Remember, if you do not chose one of the paid Auctiva Plans, it will automatically default to the Free Plan which includes the scrolling gallery).
The only problem I had was I hosted some photo's with another service and chose their scrolling gallery also... I ended up with their scrolling gallery AND Auctiva's scrolling gallery.