By default, list-only users in your member database will have normal member permissions during registration. If you want to restrict list-only from registering as members, follow these steps:

1. Access MMS Configuration
2. Locate the "Event Registration" section
3. Go to "Membership Authentication, New Members, Prospects, and Permission Options" section
4. Enable "Restrict Non-Members?". This will prevent non-members from selecting member-only packages unless they log in to their existing member account.
5. Enable "Do not give List-Only users member permissions".
6. Save changes.