The buyer has 96 hours (about four days) to pay.
After that you can open an Unpaid Item claim.
The Claim is immediately accepted, the deadbeat gets a Strike, your item is immediately relisted. Any fees you might have attracted are refunded *.
Now.
You can set up your Seller Preferenced to have the 96 hour deadline for payment automatically open the Claim.
And you can also automatically Block any bidder/buyer who has two or more Strikes for non-payment.
The likely reason for the 96 hours is that auction buyers in particular may have multiple auctions going with differing closing times. So there is some logic.
Although less than 15% of listings these days are auctions.
Sellers can also set up Immediate Payment Required, which leaves listings open until someone pays. For auctions, this is usually called Auto-Pay and the bidder has to register a credit card before the bid is accepted.
*There shouldn't be any, but I am thinking about Promoted Listing fees which are murky to me.
