Last year, OpenAI announced the OpenAI Startup Fund, a tranche through which it and its partners, including Microsoft, are investing in early-stage AI companies tackling major problems. Mum’s been the word since on which companies have received infusions from the Fund. But today, the OpenAI Startup Fund revealed that it led a $23.5 million investment in Mem, a work-focused app that taps AI to automatically organize notes.