Cleaning
Just rinse or pressure wash. For stubborn grime, any degreaser is fine, since the liner is chemical resistant. There is no coating to strip or reapply.
The first day
Use the truck normally after 24 hours. The liner reaches full hardness within a day, so avoid dragging heavy sharp loads across a brand-new liner right away.
Long term
That is really it. No annual treatment, no touch-ups. If you ever gouge it badly we can spot-repair, but otherwise it just keeps working.