Hi Rob, welcome to permies!
That was a nice present from your friends!
I think there is some good advice above, particularly that apple juice will need to be processed somehow to have a good shelf life. I think you could probably pasteurise it and then put in sterilised bottles or jars, but I haven't tried this, so don't know how practical it would be on a home scale. I think this is why (hard) cider was invented - that is what happens if you try and store apple juice!
Applesyrup look like it is easy to make (
here for example ) and you can concentrate the juice further if you have plenty, and make a fruit spread which is delicious!