You can't leave Feedback for a member who is showing as "not a registered user". You'll be able to leave Feedback only if they become registered again within 60 days of the end of the listing. eBay also removes negative and neutral Feedback left by members who later become suspended.

In addition, we don't recommend sending payment to a seller if they are not a registered user.

If you've sent payment to a seller who is now "not a registered user" and you haven't received the item after a reasonable period of time, please file an "Item Not Received" dispute. To find out about the process, and what you can claim back from eBay or PayPal, see Item Not Received Process. If you paid using PayPal please open a dispute directly with PayPal within 45 days of making the payment. Log in to PayPal and click "Resolution Centre" near the top right of the page.

If a bidder has become "no longer a registered user" since winning your auction, don't send the item to them until payment has cleared. If they don't send payment, you can file an Unpaid Item Dispute in order to claim back your Final Value Fee. As the buyer is unregistered, you'll be able to close the dispute and request a credit immediately.