[Aminkaoo]

There are a lot of premium themes available for wordpress that can be bought and used on one's site.
However, a LOT of these premium themes are leeched and put up for free by others. Any theme we like can be found somewhere for free, without us having to pay for it. The person who provides the premium theme either bought it himself and then shares it on the internet or "steals" it somehow. End users don't have to worry on how the person giving it for free managed to obtain it.
My query is how impermissible is this usage of such themes?

Suppose I merely download a theme that I know is sold for a price by its author. I didn't steal it, somebody else uploaded it and I don't care how he got it. Will this actually be a sin?