Would it be okay to drink 'Relentless' (Energy drink) every day?

If there's a phone number on the bottle, (or can,) call them and ask.

I would call a pharmacist. They are so smart and helpful.

If there's nothing on the bottle saying, "Do not use every day," then, o/c, I wouldn't. If there's no such warning, it should be okay. I'd still call a pharmacist, to be sure. :)

Yes, it is unhealthy to continually use stimulants to keep yourself going when otherwise your body wants to sleep.

You have to sleep to allow your body time to refresh and repair any damage caused by normal living. Your mind needs to rest and assimilate what it's learned. After a while, you would become irritable and unable to concentrate. Once in a while is fine, but not long term.

Not a good idea. look at the ingredients list and have a think about what is in there. Far better to use something natural like Asian Ginseng. Eat properly, especially complex carbs for energy, e.g. pasta.