Free vectors on creativevectors.org are released under following Creative Commons free licenses.
CC0 - Public domain (Free for commercial use, no attribution required)
CC0 (occasionally written as CC Zero) is a public domain dedication that allows copyright holders to place works in the public domain to the extent legally possible, worldwide. When a work is in the public domain, it is free for use by anyone for any purpose without restriction under copyright law. Public domain is the purest form of open/free, since no one owns or controls the material in any way. (Read more about this license)
CC BY - Creative Commons Attribution (Free for commercial use, attribution required)
This license lets others distribute, remix, tweak, and build upon your work, even commercially, as long as they credit you for the original creation. This is the most accommodating of licenses offered. (Read more about this license)
CC BY-NC - Creative Commons Attribution Non-Commercial (Free for personal and editorial use, attribution required)
This license allows reusers to distribute, remix, adapt, and build upon the material in any medium or format for noncommercial purposes only, and only so long as attribution is given to the creator. (Read more about this license)