How long can grape juice be kept?

I have just stripped an abundant crop of small grapes from a vine in the garden. It is not convenient to convert these into wine (lack of facilities etc), and to eat them is not really practical as they are full of seeds. So I have mashed them down, and strained the resultant rich, sweet and fruity juice into bottles, some plastic, some glass. My question is, what is the best way to keep this juice? If I store it in my cool cellar, how long will it keep? Alternatively, how long in the regrigerator (although space is a problem here)? I can get a few plastic bottle in the freezer - how about that? Any help you can give will be much appreciated. John