Looked some information up and this is what I found, "This page (the game's download page) has a unique URL for your purchase. You can always re-download the latest files from this page. You should have also received an email with a link to this page. If you ever lose the URL for this page you can request it to be emailed to you from the support page." I believe this could work if you bought the game without an account, since you likely used an email address during the purchase process.