Here's a bit more clarity. in /var/log/messages, ftp actions are logged.
Code:
grep pure-ftpd /var/log/messages
It clearly has entries like
Dec 18 08:36:09 corp pure-ftpd: () [NOTICE] /home/xxxxxxx/FileZilla_3.39.0_win64-setup.exe uploaded (7684768 bytes, 776.63KB/sec)
Dec 18 08:36:27 corp pure-ftpd: () [NOTICE] Deleted /home/xxxxxxx/FileZilla_3.39.0_win64-setup.exe