The sticking point of the confusion over Memory Maker is thanks to the terminology that Disney likes to use, and that sometimes it sounds like Memory maker has replaced PhotoPass. It hasn't.
PhotoPass still exists as it always has (though I think it's now branded as "PhotoPass+") and it now includes on-ride photos. If you don't have a MagicBand, you can tap your park ticket (which is linked to your profile in MDE) and the photos will be linked to you. Anyone who visits the park can still buy photos individually, either in-park or online after your trip. There is no requirement to have a MagicBand, be staying at a Disney hotel or buy Memory Maker in order to buy photos individually. Photos will auto-expire 45 days after they're taken.
Memory Maker is strictly a photo purchasing package that you can buy that allows you to download and save any and all photos linked to your MDE profile (as well as photos that are linked to the profiles of your Friends and Family). Though Memory Maker is linked to only one person, they can download any and all photos they can "see" in MDE.
Memory Maker gives you 30 days of unlimited photo downloads. The clock starts ticking when you download your first photo. (I've heard there's another instance that'll start the clock, but I can't recall... Perhaps sharing through social media?) If you want prints you'll have to print them yourself or bring the files to a store to print.
-Rob