A Reminder

Cactus Music
I think most of us made ISO copies of all our software a long time ago. I have images of 8.5 spread across probably 6 hard drives, most are sitting on shelves now. I don't keep anything on burned disk. Disks can get scratched and a burned disk is actually light sensitive and has a limited shelf life. The original disks will be pressed so if stored properly could last forever, but a ISO copy is easier to use.
 

This is a good article on creating ISO files. I personally use InfraRecorder, and is best to get it from the Ninite site as recommended in that article (to strip off the bloatware/malware you sometimes get for "free"). For folks with O/S' which do not natively read ISO files (Win7 is one of them), I use Virtual CloneDrive for ISO installations.
 
That said, it is also very good practice to also keep a text file in the same folder (or Excel file somewhere you can readily find) with any SN and registration codes. It is very easy to lose or misplace these, and an ISO is worthless if that gets lost.

If you're willing to spend the few extra bucks for Blu-Ray discs with inorganic dyes, they make an incredibly robust backup and archiving medium.

I realize most of my "tools" for creating and using ISO images are real old from XP days, But they all seem to work on W10. 
Virtual Clone Drive
DVD shrink
ISO Magic.  
Of course with install disks it's also easy just to Copy the disks and look after them
What a lot of people are un aware of is burned media is light sensitive unlike the originals which are pressed. Obviously a burned CD or DVD will not last if exposed to light. A pressed CD/DVD will last until it gets a bad scratch. SO that's interesting what Craig just said about Blue Ray. 

Cactus Music
I think most of us made ISO copies of all our software a long time ago. I have images of 8.5 spread across probably 6 hard drives, most are sitting on shelves now. I don't keep anything on burned disk. Disks can get scratched and a burned disk is actually light sensitive and has a limited shelf life. The original disks will be pressed so if stored properly could last forever, but a ISO copy is easier to use.
I now have a 1 TB external drive dedicated to nothing but software. It has Sonar going back to Guitar Studio and then 6 and 7 and so on. Wave lab 4, Nero 3 all sorts of stuff that probably won't run anything but XP,  but I keep it anyhow. 

If you are willing to make a gazillion copies, almost any medium will work for archiving. The DVD has gotten a bad rap for lifespan; if kept in a reasonable storage climate they will probably last at least as long as a magnetic disk drive. If you want magnetic media to last forever, you will need to refresh the data periodically. I have lost hard drives that were just sitting on the shelf, and of course one that is running is likely to die in three to five years. A USB drive that is not used except for reads is an expensive option. A good quality Blu-ray disc is likely to be the most cost effective intermediate (10-20 years) archive medium and you can make a gazillion copies cheap enough. Of course nothing beats papyrus if kept in a desert except colored mud spattered onto a cave wall. 

Before that one takes off on folks, unless you expose magnetic media (especially a HDD platter) to a strong magnetic field it isn't going to spontaneously demagnetize.
 
Every sector of every track actually has bits on it to guide the head on a read/write approach to get in on track. These are not accessible to the head for writing operations (consumers anyway - they are permanently written to the platter as part of the manufacturing process); so if these just demagnetized (which they don't), "refreshing" would be a moot point anyway because the heads would have no clue where they are.
 
For a 3.5" floppy, the areal density is so low (with such a massive margin for error) that the magnetic concerns pale in comparison to exposure to heat, dust, and general bad environment. Those I would recommend copying to something more impervious to the elements (they are essentially a more rigid version of magnetic tape and subject to the same concerns).