We would expect no clean-up activities of the cache files in APM Production. The cache files are meant to be static. The only time cache files may grow would be immediately after an upgrade or when additional customizations are made. Cache files are regenerated in the APM application using a thick-client with the administrator license but only as needed. If your cache files are turned on I would not expect their size to impact on you storage and memory significantly. However, if you do find your cache files size creeping up please report that specifically as if means there is something strange going on.
As far as other clean-up activities to conserve memory and storage, there are usually regular clean-up routines in the APM product itself. These include such activities as purging (readings) which would help reduce Database size, as well as some external purging of log files, etc.