How can I keep track of consent form agreements?

We have a web application. When the users sign up, we display a consent form based on the user type they pick. There are 3 user types and 3 different consent forms.

Now we get a new requirement that we would like to keep track of the consent form agreement. That is when the user agrees to a consent form, we would like to record that they agree to the consent form as an evidence if they sue us. The next time when they login, if they did not agree to the consent form, we will let them agree before they can login. The consent forms can get updated, so if the users did agree to an old consent form but not to the new one, we still need to let them agree before logging in.

I have a hard time thinking of an elegant way to design this. Currently we store the consent forms which are HTML files on the client side. Should I store the HTML to the backend database? How can I check if the user has agreed to a consent form or not?

Thank you in advance!