Pimple marks with a scar takes a longer time to heal.
First thing before prescribing any treatment, we need to check how is the dark pigmentation, where is it over face and if there is any active lesion in or around it.
Next Steps
You can Consult online with appropriate details for further management.
Health Tips
Drink adequate water.
Include enough fruits and vegetables in your diet.
Excercise for atleast 30-45 mins in a day for 5 days a week.
All this will help in keeping your skin and it's texture healthy.