Pro pricing?

I had decided I would like to upgrade to the pro-version BUT then when I went to purchase I saw the cost says $x.. for 1 year. Can you clarify this for me please. I use this for a single website, non-profit for personal and historical interest only. If it were a one-off fee I'd be happy to pull the trigger on it, in recognition of your fine work, but I certainly can't afford such a fee annually. Looking at it I "think" the fee covers ongoing usage but just one year of updates? Is that correct? If so, what is the benefit of the updates? Thank You. Michael.