Logoobject.com has its own license similar to the Public Domain License, with a little limitation.
Free to use
You can use logo objects anywhere without any limitation if you want to redistribute elements or use it in some editors, as templates, check the restrictions. All logo elements free for commercial use, link back is not required but will be welcome.
Vector editor, logo editor, and other editors and tools. You can use the elements as templates but you must link back to logoobject.com link must be visible space, don't need to link every object.
Redistribute logo elements, you can redistribute logo elements, but every page where the object will be located must contain a link back to Logoobject.com
Sale logo elements, you can't sell it.