I'm a big believer in printing and saving digital images to your own digital media, computer, or other storage device the moment that image appears on your screen.
You may not be able to navigate your way back to the image--even the best researchers are occasionally unable to "get back" to where they were or remember how they found something. It's even more difficult when we are researching at 3 in the morning on our fifteenth (or twentieth) cup of coffee.
Sometimes free access goes away. Images of some Chicago, Illinois, area records that were on FamilySearch are no longer on FamilySearch. This blog post on ChicagoGenealogy.com. The images may come back for free or they may now. Who knows?
In the real world, clouds go away.
There's always the chance that data you relied on "always being free in the cloud" will no longer be freely available to you.
Don't rely on what's in the cloud always being there. Get it down to the ground on your own media while you can.
