Pricing model where customers pay for what they actually consume — API calls, messages sent, rows processed — instead of fixed per-seat subscriptions. Popularized by Twilio, Snowflake, and AWS, it aligns vendor revenue with customer value but is harder to forecast. A recurring strategic question for FeatureOS and SupportWire: when does usage pricing beat seat pricing? Related to Gokul Rajaram's Work Products argument — outcomes should be outcome-priced.