var Vue = require('vue');
var Lang = require('vuejs-localization');

//Notice that you need to specify the lang folder, in this case './lang'
Lang.requireAll(require.context('./lang', true, /\.js$/));

Vue.use(Lang);

└── lang
    ├── en
    |  └──messages.js
    └── pt
       └──messages.js

//messages.js
module.exports = {
  hello_world : 'Hello World!'
}

$lang.{file}.{key}

//inside vue instance
this.$lang.setLang('pt')