I don't think you will have to worry about a virus from Keepsake. But, you do need to download to print and then you can delete. I have a flashdrive that I copy all my downloaded patterns onto so that I have them and don't have to keep going to the Keepsake (or Craftsy or epatterns, etc) sites. FYI - no matter what, you should have some sort of automatic virus protection on your computer. There are several free and basic ones.