I am a pretty heavy Seklema mat user. I’ve done a few hundred sheets on them so far.
The laser will mark the mat and leave ash stuck to it, reducing the stickiness. Optimizing power and speed as @cynd11 suggests will help slow that process.
I clean mine regularly with isopropyl alcohol and paper towels. It’s more effective more quickly than soap and water. I see no signs that it is damaging the mat.
A clean mat can sometimes be too sticky. You can adjust by sticking down an old T-shirt and removing it to add a light layer of lint.
The mat can also warp some over time and, may require additional hold down (e.g., with magnets).
There have been some previous discussions about all this. e.g.,