Can I take the SAT Subject test on a course I'm no longer taking?

I am a freshman going into my sophomore year in the fall. In June, I was given the option to take the SAT Subject test in Biology E/M because I was taking the course in school. I chose not to, but I really regret it. I was wondering if I would be able to take the test in my sophomore year, even though I won't be in Biology, I'll be in Chemistry.