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.
The real question is, why do they retain that information?
Probably so they can re-check you in the future when you inevitably renew your contract.
Not that I agree with that. It should only be stored as long as it takes to run the check.