Some schools only recognize the SAT and ACT scores, as mentioned above, for 3-7 years but you can take them at any time. Every school is so different in what they require of adult students as there are different standards and many do not consider the scores valid after a period of time due the test changing so much over the years that there is no way to compare the results.

I would check with the school(s) you are considering attending to verify the admissions requirements BEFORE spending the money and time on exams you might not necessarily need.