Amazon S3 for Easy Digital Downloads add-ons will allow you to store your downloadable files on Amazon S3, a simple and secure file storage system. With Amazon S3, your files are more secure and do not use any server bandwidth, which makes it great for all digital stores, both large and small.
When using the Amazon S3 add-on, you will upload files in almost exactly the same way as before, through the WordPress media library, but now the files are uploaded directly to your Amazon S3 account. Everything is done from within WordPress on the Download configuration page, so you never have to leave the comfort of your WordPress install.
You also have the option to select pre-existing files in your Amazon S3 bucket.