Does using a pdf for sale for free violate the 2nd precept?

So I enjoy Dungeons and Dragons a bunch, and have recently begun trying to follow the first 5 precepts of Buddhism. I'm not a practicing Buddhist, but I think they are a good way to live my life. So I have lots of PDF's that I didn't pay for bookmarked so I can use them, but since I didn't buy them would that count as breaking the do not steal precept? Thank you!