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.
It says so right there. The license is based on installs which will be tracked via downloads:
"We are introducing a Unity Runtime Fee that is based upon each time a qualifying game is downloaded by an end user.