Guidance on Copyright and License Statements

What are the recommended copyright and license statements that developers should include to protect their work?

For example, let’s say that a developer is selling a plugin in the marketplace that provides UI elements. In this case, the purchaser of the plugin should have these rights:

Allow:

  • Use of the UI elements in any games they develop.

Disallow:

  • Distribution of the UI elements, such as copying them and reselling them or giving them away for free.
  • Distribution or copying of the plugin itself.

In such a scenario, which copyright and license statements are recommended?