It is not scam. I bought the license for two devices, but after some months of use I uninstalled it. I got the feeling that my screen was too orange and that that was creating more fatigue. I said "I got the feeling", because my eye / health condition has reached a subtle point, that I do not understand anymore what is caused by what. I think I am not the only one on this forum to be in such situation. I do not want to sound repetitive, but I never considered the importance of lighting. Believe me, when I started taking my MacBook Air home and using it on the weekend, it felt another display with respect to the office environment. So my overall suggestion is to keep an eye open on everything. Most likely your eyes and / or brain are perturbed by more than one trigger. The more triggers you remove, the smoother your experience with electronics will be.
Check Iris out. They offer free trial. Test flux out. It is freeware. And maybe check also what @martin has proposed recently (Gamma Control).