Do I need a license key or serial number for RJL System Cleaner?

No. RJL System Cleaner does not use license keys, serial numbers, activation codes, or online activation of any kind.

When you register, you receive a download link for the registered .exe. You replace your existing file with the registered one. That is the entire process. The registered .exe is a separate build with all premium features enabled and the closing splash screen removed.

This means there is nothing to lose, nothing to forget, and nothing to re-enter after a Windows reinstall. Just keep a copy of the registered .exe and use it wherever you need.