This website contains age-restricted materials including nudity and explicit depictions of sexual activity.
By entering, you affirm that you are at least 18 years of age or the age of majority in the jurisdiction you are accessing the website from and you consent to viewing sexually explicit content.
I don’t know the exact modus operandi, but usually this is achieved by using some “phone home” mechanism which sends a device identifier (to ensure uniqueness) along with an OS version (and maybe some other fingerprints to ensure integrity of the data - like a hash of CPU hardware, etc).