Microsoft's GitHub Copilot, an AI-powered code suggestion tool, has surpassed more than 1 million users, according to Microsoft CEO Satya Nadella.  Microsoft and its GitHub service made Copilot generally available to developers last June.  Within a month, the AI pair programmer attracted 400,000 subscribers and now counts over 1 million users. Copilot, powered by OpenAI's Codex, an AI system trained on billions of lines of public code, suggests lines and functions, as well as other ways to solve problems, write tests, and find new APIs. Recently, GitHub said it will launch a business version, called Copilot for Business, for companies to buy and manage Copilot seat licenses for their employees. However, its future hangs in the balance as GitHub Copilot is the target of a proposed class action lawsuit challenging its legality. The suit argues that Copilot doesn't provide credit for licensed public code when it's reproduced using AI.