Your social organizing app build on matrix: think WhatsApp, but with proper task lists, structured discussion, etc.
The App (code) is made available under an the eventually Free Software "Acter Public Source License". Tl;dr: You can use the software for personal, educational and internal usage as long as the installation stays below 100 registered users and is not available to the public. Any other installation, usage or derivation of the work requires consent by the licensor. All code is made available under the AGPL Free Software License two years after its publication.
All contributors must agree that their code is licensed this way and that the license can be changed by the licensor. A bot on the Github repo will track that agreement.