npm install -g bower-license 

bower-license

├─ highlight
│  └─ licenses: UNKNOWN
├─ [email protected]
│  └─ licenses: MIT*
├─ [email protected]
│  ├─ licenses: MIT*
│  └─ homepage: http://millermedeiros.github.com/js-signals/
├─ [email protected]
│  └─ licenses: MIT*
├─ [email protected]
│  ├─ licenses: UNKNOWN
│  └─ homepage: https://github.com/highslide-software/highcharts.com
├─ [email protected]
│  ├─ licenses: MIT*
│  └─ homepage: https://github.com/millermedeiros/Hasher
├─ jquery-throttle-debounce@undefined
│  ├─ licenses: MIT*
│  └─ homepage: https://github.com/cowboy/jquery-throttle-debounce
├─ [email protected]
│  ├─ licenses: MIT*
│  └─ repository: https://github.com/AceMetrix/jquery-deparam
├─ [email protected]
│  ├─ licenses: MIT*
│  └─ homepage: https://github.com/Modernizr/Modernizr
├─ [email protected]
│  ├─ licenses: MIT*
│  └─ homepage: https://github.com/DmitryBaranovskiy/raphael
├─ [email protected]
│  ├─ licenses: MIT*
│  ├─ homepage: https://github.com/kriskowal/es5-shim
│  └─ repository: http://github.com/kriskowal/es5-shim
├─ [email protected]
│  ├─ licenses: MIT*
│  ├─ homepage: https://github.com/vakata/jstree
│  └─ repository: https://github.com/vakata/jstree
├─ [email protected]
│  ├─ licenses
│  │  └─ 0: MIT
│  ├─ homepage: https://github.com/cujojs/meld
│  └─ repository: https://github.com/cujojs/meld
├─ keymaster@undefined
│  ├─ licenses: MIT*
│  ├─ homepage: https://github.com/madrobby/keymaster
│  └─ repository: https://github.com/madrobby/keymaster
├─ [email protected]
│  ├─ licenses: MIT*
│  ├─ homepage: https://github.com/knockout/knockout
│  └─ repository: https://github.com/SteveSanderson/knockout
├─ [email protected]
│  └─ licenses
│     └─ 0: MIT
└─ [email protected]
   ├─ licenses: Apache*
   └─ repository: https://github.com/twitter/bootstrap

bower-license -e json

var license = require('bower-license');
license.init('/path/to/package', function(licenseMap){
    console.log(licenseMap);
});