When you have pickled it keep it somewhere dark, I have some from 3 yes 3 years ago and it's still fine. I've kept it in the shed under some cardboard/sacking
In my opinion beetroot should never, ever be pickled - that horrible vinegar taste destroys all the earthy sweetness of these delicious roots. Just lave them in the ground until you're ready to eat them fresh in so many different ways.
Don't freeze pickled beetroot it keeps for years as long as you don't open the jars. Pickling is another method of preserving it as is freezing, you do not need to do both.
Be sure to waste the greens... they freeze very well and are wonderful on a cold winter's evening as a slad or cooked with a little bacon... after removing any tough ribs just blanch them in boiling water for no more than 2 minutes or so, dry them ever so slightly and place in a freezer bag... et voila!
We put them in a vacuum freezer bag, but one doesn't have to.