All textures on textures.pixel-furnace.com are free to use for non-commercial and commercial projects.
The materials provided are optimized for real-time performance and realistic appearance. Additionally to the albedo/diffuse map, they include bump and normal maps, as well as specular, roughness and metalness for extra details. Most of those texture maps are sized in power of two dimensions, maximizing resolution with minimal memory consumption.
Providing credits is not required (but appreciated) when using our textures.