Long story short: I have a slightly older machine with a largeish (as SSDs go) SSD with all sorts of stuff on it, and 10.7. I have a slightly newer machine with no SSD and 10.8. I am not totally sure whether the new machine would boot and run from the old machine's drive (it's a June 2012 MBP, non-Retina, so I think it came with 10.7 originally, but there might be Deep Magic in the stuff that interacts with EFI...). I don't actually care that much about 10.8, but if at all possible, I want to avoid either (1) having to wipe out and reload from backups or (2) paying for a 10.8 upgrade I don't actually care about right now. The newer machine was just-purchased refurb, so it qualifies under up-to-date, but I don't know how that is verified or checked, or whether it'd work if it were using a 10.7 hard drive. If not, but it ran okay, I wouldn't actually feel particularly put out. So mostly I'm seeking advice/ideas. Do the non-Retina 2012 macbooks work with 10.7.5? How does the up-to-date program check eligibility? (Or are all of the June 2012s eligible, in which case that'd at least explain how it knows it is entitled to 10.8.) Is there an apple recovery option I overlooked for "keep this drive's user data, apps, and settings, but upgrade OS X to 10.8 if you need to?" EDIT: A few notes: I've never bought 10.8 as an upgrade. So even though the new machine has 10.8, it doesn't appear that I can use it to obtain the 10.8 installer, which I would need to have to run an upgrade of the existing drive. So far as I can tell, anyway, regardless of which drive is in the machine, or how it is connected, the new machine has no options other than "fresh install of 10.8". This wouldn't be an issue, except that in this case I want to use that specific drive, because it's an SSD, and I don't have another SSD large enough to replace it.