"Electric Coin Co. is spearheading a new type of open-source license, one that enables anyone to commercially support and improve software while ensuring that all improvements are open source after a set period of time. This license, the Transitive Grace Period Public License, TGPPL for short, is a way to make open source more resistant to capture and more sustainable."
"[...] to distribute or communicate copies of the Original Work and Derivative Works to the public, with the proviso that copies of Original Work or Derivative Works that You distribute or communicate shall be licensed under this Transitive Grace Period Public Licence no later than 12 months after You distributed or communicated said copies"
Example use: https://github.com/zcash/halo2/blob/main/LICENSE-TGPPL
"[...] to distribute or communicate copies of the Original Work and Derivative Works to the public, with the proviso that copies of Original Work or Derivative Works that You distribute or communicate shall be licensed under this Transitive Grace Period Public Licence no later than 12 months after You distributed or communicated said copies"