> The core of Ethereum includes the consensus engine, the networking code and any supporting libraries. For C++, this includes libethereum, libp2p, libdevcore, libdevcrypto, libethcore, libevm and libevmface.

> The core of Ethereum will be released under the most liberal of licenses. This reflects our desire to have Ethereum used in as many diverse environments as possible, even those which, for various reasons can require modifications or augmentations to the software which cannot be released to the public.

https://github.com/ethereum/wiki/wiki/Licensing