is merit slimming tablets by sari-sehat regisered by fda and does it
mean its aproved and safe to use

Sari Sehat is an Indonesian company that distributes herbal products.
I have found no list of ingredients for "Merit," but I caution you
that many herbal weight loss products contain dangerous ingredients.

Here is an article that may be helpful:

http://nccam.nih.gov/health/supplement-safety/

Here is some information on the FDA and dietary supplements:

http://www.cfsan.fda.gov/~dms/ds-oview.html#getinfo