FamiStudio
This is the only official "free license." You get full premium access for 30 days with no credit card required. After 30 days, the software enters a limited "nagware" mode (it still filters blue light but disables features like custom intervals and presets).
A: No. Careueyes writes a registry key and creates a hidden file in AppData . Even after uninstalling and reinstalling, it remembers that your trial has expired. Only a fresh Windows install would reset it (which is extreme overkill). Careueyes Free License Code
CareUEyes offers a basic free version that includes essential eye protection modes, though Pro features like advanced scheduling and additional filter modes require a key. This is the only official "free license