OpenAI kicked off "12 Days of OpenAI," an event with announcements across 12 weekdays, launching on day one the $200-per-month ChatGPT Pro plan and the full version of its o1 reasoning model. Pro includes unlimited access to OpenAI o1, GPT-4o, and Advanced Voice, plus o1 pro mode, which uses more compute for the hardest problems. The event went on to deliver major releases including Sora's public launch and the o3 announcement.