At the moment, the user policy in Moodle is just a one-time solution.
As soon as a user has accepted the user policy, he is allowed to access Moodle even if the user policy changes sometime in the future and there would be the legal requirement to have the user accept the (changed) user policy again.

Based in the work in MDL-46553, we propose to create a new feature:

• If the user policy is set in the Atto editor, the policy settings page should check if the user policy was changed at saving time. If it was changed, it should ask the admin if the policy acceptance of all users should be reset.
• Additionally, there should be a button on the policy settings page which lets an admin reset the user policy acceptance manually. This is the support special cases when a user policy in the Atto editor refers to some third party user policy document or the case when a user policy was set as an external URL. In both cases, Moodle would not be able to detect changes to the policy itself.
• If the policy is reset for all users, the policyagreed field in the mdl_user table will be reset so that all users have to accept the user policy again.
• If it is technically possible with the existing policyagreed field in mdl_user, it would be great if there could be a difference between users who have to accept the policy for the first time and user who have to accept the policy again because it has changed. In this case, a string "The policy of this site has changed. You must agree to this policy again to continue using this site. Do you agree?" should be displayed instead of the current string "You must agree to this policy to continue using this site. Do you agree?" (policyagree)