I follow this:
Do not copy a pattern to give or sell.
Do not claim a design or pattern of another as your own.
Anything other then that are rules the designer or publishing co want you to follow. Rules are not a legal matter. The rules are always listed right under the copyright law making it appear as part of the copyright.
It's legal to show how a pattern is made (tutorial) but not copy any text or image from the original pattern.
Neighbor's law firm represents a big craft/pattern publishing company.