Whether or not copyright is an obstacle depends upon the license agreement of any Refills you use. Some creators of Refills make no limitations on your usage of them, while others specifiy in the license agreement that you must inform them of any commercial use of their sounds. If you want to use Reason professionally and don't have the money to pay royalties or license fees, then the best legal advice is to not use any products in which the license agreement requires any notice or compensation to the originator of the sounds. Otherwise, you can make whatever use you want to of all the Refills that came with Reason or any that you've bought or downloaded for free. Just be sure to actually read the license agreement, so you know exactly where you stand. But, other than that, the software was made to be used and the product of your use of it is yours and no one else's.

Gary