Currently I store all rules files on the file system (there are lots of versions of them) and load the different versions of them into memory at startup. I would like to change
I also faced same scenario. I stored all Rule files in database.
When loading rules at application startup, I got the rules from database and stored them in temporary folder for compiling and putting them in Rule Base.
If your rule changes during running application, update the changed rule in Rule Base with the same way.