Raczej bezpłatne.
Znalazłam taką definicję:
Stock photos are professional photographs of common places, landmarks, nature, events or people that are bought and sold on a royalty-free basis and can be used and reused for commercial design purposes.
Some conditions of use may include things such as use of the images is licensed, not sold or in case of a stock photo being used in a magazine there may be a maximum number of copies of the image allowed to be printed under the agreement. Terms of Service policies will differ between stock photography distributors.
Czyli lepiej się upewnić co do warunków.
Pozdrawiam