OP might be concerned with not having a CDROM in their machine. Same concern that many of us may have in 20 years.

I have older software on 3.5" floppy disks that I can no longer access, and fortunately have the disk images.

You can get a 3.5" drive with a USB cable. Works well.

Thanks, i'll look into it as a secondary backup.

"Usually"

Not sure I'd trust my only copy of something I want to keep long term to a "usually."

My CDs from 1986 are fine.