Familiars retaining magical powers

I understand that a Familiar retains its magical powers if the mage can convert them to the Hermetic equivalent.

But what of powers without Hermetic equivalents?
Say a magical beast sheds irs skin once a year, leaving behind in the shed skin a single gold scale worth 1 pawn of Vis. Said beast agrees to become a Familiar. As a Familiar, does it retain the power to produce the yearly Vis?

The familiar keeps all their powers in 5th ed. not sure about other editions that you might play.

I think you confused the rules for binding a familiar with the rules for opening the gift...