gitlab pages artifacts expiration?

In, for example,
https://gitlab.common-lisp.net/cmucl/cmucl-site/-/jobs/1316, there's a
note on the right that the job artifacts expire in 3 mo.  There's also
three buttons for keep, download, and browse.

So, if I run CI for the latest changes and don't touch the site again
for 3 mo, all the generated pages will disappear?  That would be bad
if the webpages disappeared after 3 mo.  It would also be annoying if
I had to make changes at least once every 3 mo to keep the site up.

How does this work?  Googling for this didn't actually answer this
question, except to say I can set expiry_in to some large value to
preserve the artifacts.

-- 
Ray