Pretty much what everybody else has said.
It's basically a placebo effect, and it working depends on how desperate the person is. If the person desperately wants to lose weight, they are going to follow the diet and exercise instructions perfectly, so yah, it will work.
Will it help depression? If it works, most likely! A portion, at least, of people's depression is usually their weight. Lose weight, less to be depressed about. Same as anxiety. Have somebody feeling better about how they look, they'll likely start feeling less anxious about things. Is it some miracle drug that helps you lose weight, become less depressed and anxious? Not really, since there's likely a correlation between all three. Lose the weight, the depression and anxiety will start to go with it.
Sure, you got a certificate for $12 for a 60-day bottle... but it will say for best results, try at least for ___ days, you'll start to see results (from diet and exercise) and then you'll be sucked into paying $50 for the next 60-day bottle. They know this. That's their plan.
A friend's father tries a new fad diet pill often. Looking at the bottles, there's... absolutely nothing in them that actually points to weight loss. But, anybody can do diet and exercise on their own, the company is here to make money! So they put some herbs into a pill, sell it to you, and then tell you a diet and exercise regime so it looks like it's working, and you keep coming back to them.
If you want to lose weight, and you've been trying by yourself with diet/exercise and it doesn't seem to be working, don't go to "a pill". If you have a little money to throw, speak with somebody (or there are places on the internet!) and get a diet/exercise plan formulated for you. Then it will be food you'll eat, exercises you have the ability to do, and results.