What It;s Vivre Card ?

Vivre Cards (ビブルカード Biburukādo?), also known as "the paper of life" (命の紙 Inochi no Kami?), are a special form of paper made in the New World. A Vivre Card is made from part of a person’s fingernail which is then made into paper. It is completely waterproof and fireproof, but can be torn and given to a cared person that one would be separated from. The torn piece will point to and move towards the largest piece of the Vivre card (as shown with Rayleigh's card) while the largest piece will point towards the person the Vivre Card was designed from (as shown with Ace's Card). However, if a Vivre Card begins to burn on its own, that means that the life of the person who gave the Vivre Card is vanishing

Vivre Cards Received by Straw Hats.
Portgas D. Ace: The very first Vivre Card received in Arabasta to help Luffy find his brother. It has diminished quite significantly due to Ace being captured and in danger of execution.Upon rescue from the execution scaffold, the card has been restored fully, but when Ace took a direct hit from Akainu through his stomach and died, the card perished.

Lola's Momma: Received from Lola of the Rolling Pirates, she gives Nami a Vivre Card of her "momma" in case they need her assistance in the New World.[4] Here the importance of the Vivre Card is fully explained.

Silvers Rayleigh: After the trouble they caused on the Sabaody Archipelago, Rayleigh gives each member of the Straw Hats Crew a Vivre Card to find him once their ship has been coated.
Unknown Person: Just before the Straw Hats leave Sabaody Archipelago for Fishman Island, Shakky gives them a Vivre Card to an unknown person, telling them that that person was "counting on it".

Translation and Dub Issues.
"Vivre" is the French word for "to live".
Some translations refer to it as "Biblicard", possibly due to its Japanese pronunciation "Biburukādo".