Is one who disseminates information from an educational course or its summaries, after becoming aware of the instructors' condition not to publish, sinful, even though this condition was not mentioned at the time of sale?

Intellectual property rights are protected and may not be infringed upon. A participant in courses is not permitted to publish their content if the organizing body stipulated that they should not be published. The prevailing custom is that paid courses do not allow their content to be published, and what is known by custom is like a stipulated condition. Therefore, you must adhere to not publishing the course content.