It's a good article from Nat Geo. I wish as scientists we were better at instead of saying "up to a year" we say "we tested for a year" or "at least a year" because none of the 12 patients suddenly had no spike protein anymore at 12 months.
The paper itself uses "up to" themselves in their abstract, but makes it clear in their results that they only tested for 12 months in the study:
"...blood samples were collected two or more times up to 12 months after their first positive result..."
https://www.medrxiv.org/content/10.1101/2022.06.14.22276401v1.full-text