Ensure that new member sign-ups and renewals agree to your Terms of Service, Terms and Conditions, Waiver, Member Agreement etc. Set a mandatory Terms of Service checkbox in your enrolment flow that is required for the user to complete the sign-up process.
From the Admin panel:
'Settings' > 'Apps' > 'People' > Terms of Service
Enter the page URL* that hosts your Terms in the 'Terms of Service' Link. There will now be a required checkbox on the first page of your signup process.
*You can easily create a simple webpage that hosts your Terms of Service text. For more information of creating additional webpages on your SilkStart site, see: How do I create new custom web pages on my site?