Once the images are received by you, I am no longer contractually responsible for their safekeeping. That being said, my standard practice and my continued intention is to retain all of my images indefinitely, both for my own uses and as a courtesy to my clients, and there have been several instances where a past client has asked for the image files to be supplied again due to a catastrophic event or inadvertent loss, which I was happy to provide. However, please keep in mind that for these older weddings that have been delivered, I don't maintain the same number of redundant backups as I do with weddings that are in the process of being edited, so there's certainly a possibility that I may not still have your images available at a later date.
So please remember to make multiple backups of your images and keep at least one copy in a different location. Additionally, you should periodically copy/verify the images to new storage devices, to protect against degradation from old age, and to stay ahead of media obsolescence. And don't forget, printing your wedding images is the best way to ensure you and future generations can enjoy them! I've written a helpful article with more information about how to properly preserve your digital images.