My NFT sold — when do I get paid?

When you collect it. The winning bid goes to the auction contract, and it stays there until you withdraw it — the same way a losing bidder has to reclaim their own bid.

Open the auction from your account and withdraw the proceeds; confirm in your wallet, pay the network fee, and the CRETA arrives at your address.

So a sale you have not collected is not money missing. It is money you have not picked up, and it does not expire.