How works the File Transfers system ?

I've don't understood the quotas permissions.

It seems to be a quota by month.
(virtualserver_download_quota & virtualserver_month_bytes_uploaded)

Nothing about that in the documentation btw ...

- when this quota is reseted ? the first day of each month ?
- how to reset manually the counter ?

If I have a quota of 10 MB, if I've uploaded 10MB of files
on the server, how works the server the next month ?

I can upload again 10MB of more the next month to have a total of 20MB used on the server disk ?
Or I've need to delete old files before ?

Thanks for your answers,