For as long as it's valid (not outdated or unmaintained), keep the option to claim the stickers and see the information for the crisis line.
Don't have it tied to the marketplace as an expiring listing, since people won't be able to claim it after it expires, but rather have it be "it's own thing", if you know what I mean. For example, maybe a permanently available redeemable thing since it's free. Or, redeemable from some special information page related to the crisis line and mental health resources.
My reasoning is that having it presented as a temporary store item kind of contradicts the supposed premise, which is to spread awareness of the crisis line affiliation.