The first thing I have always done when downloading
any software is to write all the installation files together with receipts and installation keys to 1. high quality CD or DVD 2. an external USB drive that I set aside for the purpose and 3. My NAS RAID1 drive. At that point I have got 5 x copies of all the files and
only then do I start installing.
Once you've bought something, it becomes your responsibility to look after it but I'm sure that eventually customer support will provide you with another download link given that you have provided proof of purchase.