I have started deleting images that are over 3 months old. Any images that have a path starting with http://hyenacart.com/prod_images2 will be deleted in the next 48 hours. If you have images that need to last in your store longer than 3 months, then you have a few options: 1) host these images remotely, on your own server or somewhere like Photobucket (although I think images expire there too); or 2) upload your long-standing product images to your gallery, then copy that image path to your product listing.
Note that category images and gallery images will not be deleted, only product images. I’d like to keep them all up forever but there’s just no way the server can handle all these images indefinitely.
Thanks!