Do you store the fact a user has accepted your terms and agreements and privacy policy?

Basically the title - do you just have it as a checkbox that restricts sign up unless checked or do you actually store the fact that they have agreed?

For Kampsite I'm currently storing these on every signup as a JSON blob but becoming a bit of a pain to maintain and keep up to date when it changes, so just wondering if this is really needed and I'm just being paranoid, or if there's an easier solution or existing service out there that will handle this for me.