it is possible that the license agreement permits the refund after a longer period of time. there are benefits to some license agreements or purchase arrangements for the buyer, but they are paying more up front.
there are no laws (in the US) regulating refunds, but most banks voluntarily negotiate refunds for as much as 6 months after purchase. the refunds are negotiated between the financial institutions (the payer and receiver).
the stock media agency can offer refunds to whatever limit they desire.