Extra copies of Risk of Rain in HB: what will disappear?

Below all the bundle steam keys, the extra copies of Risk of Rain are shown like this:

"Risk of Rain
https://humblebundle.com/s?gift=xxxxxx
Gift a copy of Risk of Rain by sharing the link above!
These keys must be redeemed by November 25th at 11am PDT"

But once that humble gift link is redeemed, the gifted page says:

"Risk of Rain
Click the button to redeem on Steam
Steam Instructions
Steam will not provide extra giftable copies of games you already own."

With no expiration date, and a regular steam key is provided once we click on the redeem button.

So what will really expire, the humble link or the steam alphanumeric key? Maybe once that the HB link is redeemed the steam key will be safe to keep unredeemed for longer? What do you think?