How long are my Polos available? Do they go away?

Currently, your Polos are available until you decide to delete them, unless you stop using the app for a year or more. The only chats that are deleted entirely are those where all users in the chat have not opened their Marco Polo app for 365 days or more.

Shared Polos can be permanently deleted by the sender as described here. 

We archive most Polos that are 30 day old or older for Free users. Restoring a chat from the archive will take at least 24 hours. We do not archive Polos for Plus users or in chats with Plus users, including groups.