From National Bank of Poland web-page (http://www.nbp.pl): 

Approval for the reproduction of the money designs

The National Bank of Poland as the issuer and the owner of property rights related to the money designs reserves itself the right to grant individually its approval for the reproduction of the money designs in order to exclude any case of their copying in any form that devalues the Polish money. Due to the issuer's necessity to ensure the safety of the banknote circulation, such an approval is usually secured with the requirement to reproduce only one side of the notes the size of which is decidedly different from the real one.

The National Bank of Poland does not charge any fee for its approvals for using the banknote or coin designs for advertising purposes.

Moreover, according to the applied regulations of the Act on copyright and the related rights of February 4th, 1994 (Journal of Laws No. 24, item 83) that provide for the observance of personal copyright, the author's permission is needed in order to use his work. Without the author's permission, the elements of or the whole work that is put into circulation as a legal tender or its elaboration for other purposes than the ones connected with its official function of a legal tender must not be used.

In view of the above mentioned, in order to get an approval for using the pictures of banknote or coin designs, one should apply to the NBP attaching, if possible, the project of an advertisement. After getting the approval from the NBP, one should contact the author of the banknote or coin design in order to get his approval as well.