Whats likely to happen if I take 4/5 tablets instead of 2

I've been starting to take the Focus Formula tablets to help jog my memory and focus, its been working pretty well, but I have a big science test coming up tomorrow and I wanted to double up on the dose (recommended 2 tablets, one in the morning and one in the night), is it safe to double up and would it make a difference. It has DHA, huperzine-A and vinpocetine

You should follow the directions on the packaging. They are there for your safety. Well, and also so you don't sue them.
Just study. My prof. said to take a break every 15 minutes while you study. Also, study before you go to bed, then again after you wake up. This always helps me.
Much luck!