1. CC0: Offers maximum freedom, waiving all rights. MIT: Allows use, modification, and distribution with attribution. GPL: Requires derivative works to be under GPL, ensuring open access.

  2. Qualcomm: Blending open source and proprietary tech, leveraging open source to enhance proprietary offerings.

  3. Red Hat: Providing enterprise-grade support for open source solutions, monetizing through service subscriptions. Despite open source reliance, businesses offer proprietary add-ons, services, or support for income. They comply with license constraints by balancing open contributions with proprietary elements, sustaining revenue while upholding open principles.