Betterment asks you to invite only people you know personally, and requires you to disclose that you are compensated for the referral.
What the clause says
Betterment's referral terms ask that you send invites only to people you know personally who will be glad to get them, and they carry a disclosure the referrer is expected to pass on: that they are a Betterment client and receive compensation if the new account is funded.
Why it is stricter than it reads
The word please makes the sharing sentence look like etiquette, but the disclosure requirement is not optional and the surrounding terms treat a referral as a testimonial advertisement, with the referrer warranting they are not an ineligible person. Betterment is a registered investment adviser, so this sits under the SEC Marketing Rule rather than under ordinary promotion terms. Public posting is effectively off the table.
Two different windows
The cap is five sender rewards in a calendar year. Separately, once you have filled five referrals you do not become eligible for further referral promotions until the first day of the month beginning after 365 days have passed since the end of your earliest active promotional offer. Those are different clocks and it is easy to read them as one.