OpenAI will move Plus, Pro, and Business subscribers to a single usage allowance shared across ChatGPT and Codex starting in December 2026, according to a notice published on the company’s Help Center. Instant chat will not draw from the shared pool. Under the new structure, usage for ChatGPT and Codex will be measured in tokens, the units of information a model processes and generates. OpenAI said how much of the allowance a subscriber consumes will depend on the model chosen and the task…