The amount of levels are infinite! As long as new users are completing the sign-up process when being referred, the link can continue onto an endless amount of people.
Your client simply needs to share their Referral Link with a friend, family member, coworker, etc. Then the new user needs to click the link and sign up for a FOREVER account in that same session. They will automatically "tag-along" to have the same Ambassador the referred client has.