I am just thinking out loud, but what is the point in taking the AP Spanish Language exam and getting credit when you are a senior and the school you are going to does not have a language requirement for your degree plan?
I took the CLEP test at the local U where I enrolled. They placed me in 2nd semester, 2nd year Spanish. Upon successfully completing that one course I received credit for that course plus the 3 semesters leading up to it. Those credits counted toward the total # of credits I needed toward my degree though my I had no foreign kanguage requirement for my major either. It gave me advanced standing earlier, so I could register earlier than otherwise and was more likely to get the courses, sections and teachers I preferred.
I also took a test and was exempted from intro to psychology. Between my Spanish credits and psych, that totaled an entire semester worth of credits for the price of two exams. Of course, ymmv.
Having these credits gave me more flexibility to take more courses to explore and also allowed me to devote a lot of time and energy to writing an honors thesis so I could graduate with honors from college in my major (sociology). In turn, I think that graduating with honors also helped me get admitted to my preferred grad schools with good merit awards.
If you are not planning to take a higher level Spanish course in college, then probably none.
As Hlmom pointed out some universities give “retro” credit for the courses you skip. Say you get a 4 on the AP test, at some schools that gives you credit for the 4th semester of Spanish. Then if you take the 5th semester and get a certain grade then you get credit for the 3 semesters you skipped. If you attend a university where your enrollment is based on how many credits you have, these language credits can be very helpful. Also, many degrees include some amount of elective credit that may be filled with these language credits.
If you transfer to another college, or apply to a graduate program that has a foreign language requirement, it may be useful. However, it may not be that critical, since many colleges have their own foreign language placement tests anyway.
At my school, my AP Spanish credits count toward number of credits required to graduate
You might change your major.
If the school you have admitted already and decided to attend does not require FL or not offering AP credit on it, you may skip the exam. Note that you will still need fulfill electives at college, so any credit may still be useful even it is not required. Nevwrthkess, if you are unlikely to get the score required for credit, you can save that $100. My D’s engineering school does not require FL, but she got 8 credits from AP Spanish and placement exam to fulfill electives requirement. With some other AP credits, she only needed one 3 credit 200 level elective to fulfill all her elective requirement.