Guild Wars 2

If I complete the Living Story on one character, will I be able to run it on another character in say 6 months? Or will I have to purchase the unlock for that character?

The patch notes state doing the living story unlocks it, but is it an account unlock, or a per character unlock?

Account, see https://www.guildwars2.com/en/news/introducing-the-story-journal/

It unlocked on all my characters, including ones that aren’t level 80 yet. It was also unlocked for a brand new character I created after the update.

We can’t check yet to see if unlocking it also gives it to any characters you create after the release is over, but I assume it will based on the description.