Significado da licença MIT

1. Você pode vender o software.
2. Não, você não é obrigado a fornecer o código-fonte.
3. Qualquer pessoa que receba código-fonte pode fazer o que a licença permitir. Isso não se estende a distribuições binárias.

Leia a licença do MIT. Leia a coisa toda e entenda. Foi concebido para ser lido por pessoas comuns, ao contrário de outras licenças que são muito complexas:

Copyright (c) year copyright holders

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

De acordo com "Entendendo o código aberto e o licenciamento de software livre" por Andrew M. St. Laurent :

These licenses, as applied to the original licensed code, allow that code to be used in proprietary software and do not require that open source versions of the code be dis- tributed. Code created under these licenses, or derived from such code, may go “closed” and developments can be made under that proprietary license, which are lost to the open source community. For the same reason, however, these licenses are very flexible and compatible with almost every form of open source license.

Como sempre, consulte um advogado. Se esta biblioteca for liberada estritamente usando a licença MIT, então:

(i) Sim, você pode vender seu software desde que inclua a licença do MIT como parte de seu produto. (ii) Não, você não precisa compartilhar seu código com a comunidade, mas seria bom. (iii) Sim, a revenda é permitida.

Licença MIT:

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.