Adobe PDF Service API Free Trial

I am looking for a solution for extracting tables from PDFs. Those tables are text-based, not scanned images. I encountered Adobe PDF Service API. The website says each clientID can have 500 free trials per month. However, I receive error message of free trial exhausted after processing about 20 PDFs, and, oddly, the API reports no activities in my project. Why does this happen? Thank you in advance for any comments.