While a free portable version exists, the version (which requires a license key) unlocks several automated tools:

Automatically cleans browser history and temporary files when you close your browser.

Allows you to set the tool to run at specific times (though users often prefer the installed version for scheduled tasks). Security & Usage Tips

Before using the Registry Cleaner tool, always allow the program to create a backup of your current registry settings in case you need to undo changes. CCleaner 6.24.11060 Portable - Registry tab hasn't moved

Recent versions may have third-party analytics enabled by default in the Data\usercfg.ini file; you can manually opt-out in the settings.