Apache logs .bkup and its rotation

Hi,

I was looking into the logs in cpanel and there were some .bkup files. A minut or something later, those files were gone. I got a little bit worried my server might have been compromised, not on this but on another vulnerability, but I do think this happened for some configuration. Can you let me know the script that takes care of this?

When, how and why are those .bkup cleaned. Also I don't seem to be keeping any historic logs, only some for a day, what should I configure to keep longer dated logs for apache?

Thanks,
Ariel.=