The process of managing a portfolio of copywritten material includes its monetization with planning. Licensing is best and only real way for copyright owners to earn income for their creative works (of course, sales being the other).

But wait, you say. What is licensing? It has been defined as the following to keep it simple:

Giving a license to use any of your intellectual property is actually permitting them to use the licensed item(s) for their activity;

1. By granting a license to someone or a company, you are actually authorizing the recipient of the license to use what you have created;

2. A license gives permission to an individual or company to do something that they want with your intellectual property;

The potential of earning a an income as the result of licensing the use of your material depends upon its quality, its potential market, and the terms of your license.
It is the terms and conditions of your license that is of most concern from a legal perspective.

This is most certainly a case of avoiding a disaster by having your license reviewed and/or prepared by someone with knowledge of these agreements and the ways in which you can both protect your intellectual property and to maximize its income potential at the same time.