You can clean your PC manually using Windows' own utilities, which are often safer than third-party software:

: When searching for free license keys online, be aware that many sites claiming to offer free keys may host malware or fake software. Always use reputable sites and consider purchasing directly from the software developer for security and to support the developers.

: A completely free, open-source alternative to paid cleaners. It is highly effective, transparent, and contains no "pro" upsells or ads. BleachBit Official Site Microsoft PC Manager

: This tool provides a comprehensive set of utilities to clean, optimize, and protect your PC. It offers both free and paid versions, with the free version covering basic cleaning and optimization needs.

: A popular choice for PC cleaning. It's available for free, but the Professional version requires a license key. You can try searching for a free trial or looking into their official website for promotions.