Lucy memorializes their adventures with pen and paper, bent over her desk with her window cracked open for the fresh air. Her writings line the shelves on her wall amidst her fictional tales, separated neatly into soft leather bindings; she has three shelves now, installed with the help of Erza and Gray, though she's only managed to fill the first two.
(Natsu tried to help, but after setting four planks of wood on fire and almost breaking her window, Lucy had to kick him out.)
Some of them are worn, the paper dusty and crinkled from seven years of neglect, and while this is another of the things Lucy regrets, she will not let it deter her. Instead, she handles them with extra care, turning the pages carefully and reminiscing fondly.
Fairy Tail is her home, now more than ever, but the world moved on without them, left the guild and their legacies to rot. She will not allow that to happen again, will preserve their stories so they are not lost in the years like they were.
Lucy writes because she wants to, but she also writes so that they - her family, her nakama - will be remembered.