How to print LiDAR file format LAS
Because my research shows that LAS files are point cloud data, you would first have to convert the point cloud to a mesh. Point clouds are just that, data references to points in 3d space. A printing service works with files that represent planar surfaces, properly joined (watertight, aka manifold) to form a solid or solid surface model.

The only resource I was able to find involves using Meshlab. There are two reasonably practical references for this process.

The first is somewhat generic and provides the conceptual information:
Point Clouds to Mesh

The second appears to be a more step-by-step method:

Point Clouds to Mesh (2)

I would expect that if you are successful in creating a mesh from your data, you would then want to use a program suitable to determine (and repair) any non-manifold portions of the model. There are many available, including Meshmixer, although the others have escaped my alleged mind at this moment.