What happens if you stop iTunes Match subscription? If you cancel your iTunes match subscription, what exactly does happen?

Can you still download the songs you matched already, but cannot match any new ones? Or can't you download any song anymore? Will the matched songs you already have downloaded on your Mac or iOS device be deleted or will they be kept?
You will no longer be able to download like you currently do, and in effect, iTunes will act like Match was never on.

You will be able to keep any songs you downloaded, though. So if you upgraded files you uploaded that matched to iTunes-Plus-type files, then you keep those once it cancels.