By default, Plesk removes/rotates log files every 24 hours.
How to increase the storage period for IIS logs in Plesk for Windows?
To increase retention of IIS logs, perform the following steps:
Connect to the server via RDP
Open Command Prompt as Administrator and execute the following command:
REG ADD "HKLMSOFTWAREWow6432NodePLESKPSA ConfigConfig" /v log_pleskwebsite_history /t REG_DWORD /d 42 /f
In the command above, replace
42with the value in days the logs should be kept.