I started to talk with this Spire upgrade and I see now several discussion about it and also on Loyaltylobby
So as I said I have renewed in July my AMB. I never noticed the end of my spire status until September when I saw 31 dec 2017...
I called them several time to check the validity of Spire and they told me 2017. So one day I asked them why do I have it one extra year as complimentary and they informed me that during the renewal of my ambassador I got it. But the agent told me it is a one time only offer...
Right now I achieved 75K but I want to see if it will be extended to 2018.
Upon reading the terms I found this :
" Upon purchase of InterContinental Ambassador status, IHG® Rewards Club members who are Club or Gold Elite members will receive Gold Ambassador status upon enrolment.
All InterContinental Ambassador members can earn Platinum Ambassador or Spire Ambassador or be invited to Royal Ambassador status. "
But now I believe with all the discussion on different website they will stop doing like that.