Each local council area has differing legal requirements regarding the boarding of dogs, please contact your local council to be clear on the rules and regulations before you board dogs in your home for daycare or overnight stays. Dog walkers should also be aware of off-lead times in local parks as well as on-lead and off-lead areas in general.
If you are in Hong Kong, a license is required if you plan to offer services in your own home (home dog boarding or doggy day care). You can find more info here: http://www.pets.gov.hk/en_business_3_2_list.php#btop