I did earlier in the month using that link. Though I'd tried phoning them to see if they'd just honour it without me doing anything and was told by the (quite snappish) young man that there was no such offer available. I just said ok so I'll just cancel then.
set my own sub to not auto re-new (and the original card had expired anyway)
I save absolutely zilch on ancestry (no tree, no nothing) so renewed as my OH, and the 3 weeks or or so still on my own sub was donated to someone else - its nice to be nice :-)
Win win situation :-)
Boo