This should not remove License

[vko-online]

I belive this app is what i want, but don't remove license agreement, it would be fair right?

[BradDenver]

I'm a little unsure what your question is.

Are you wanting to use Preen to remove files but not licences? I can show you an example of that if thats the case.

[vko-online]

yes please ^{those license files usually don't have extensions}

[BradDenver]

The following bower.json is an example configuring Preen to keep the contents of the assets folder and the LICENSE file for bootstrap-sass-official

{
  "dependencies": {
    "bootstrap-sass-official": "~3.2.0"
  },
  "preen": {
    "bootstrap-sass-official": [
      "assets/**",
      "LICENSE"
    ]
  }
}

You should be able to adapt this example to your needs.