As of OpenAI's DevDay this week, ChatGPT Plus and Pro subscribers can spend their plan inside 16 outside apps. More than 50 million people pay for ChatGPT. A chat subscription just started acting like a wallet. AI bills stack up fast. Menlo Ventures found the average US consumer uses 3.0 AI assistants, up from 2.2 a year ago. Consumer AI spend more than tripled to $40B. My guess is a big share of that spend pays for the same few models, once per app. A team of agents makes a lot of model…