When you see a design in a magazine or book you bought,it is fair game and there for you to use. The only thing wrong to do would be to use the pattern and copy it and sell it. If a designer wants you to pay for the pattern, she won't print it out for the public to see and use.
If you pay for a quilt design, copy it and share it with others, that is wrong and against copyright laws. You have to ask permission from the designer to use her design and if she gives permission for you to share without paying more, that is legal, but she has the right to ask you to pay for more patterns. Even if you do use a pattern from a book or magazine, it is proper to give the designer the credit so others can go to her for the pattern. If it is your own creation, you will want others to honor your work and not say it was theirs when you know you made it up in the first place.
Carol J.