Use a simple spreadsheet to record the details of all your closed auctions.
eBay is not your keeper. They won’t pick up your room, they won’t do your homework, and they won’t keep permanent records of your completed auctions.
If you sell on eBay, you’ll need to keep some semblance of records of all the items you’ve sold. You’ll need to keep track of who your high bidders are, whether or not they’ve paid, and whether or not you’ve shipped. It’s very easy to do, and all that’s required is a spreadsheet or database (suitable applications include Microsoft Excel and Microsoft Access, respectively, both included with Microsoft Office). If you’re not sure which one to use, see Spreadsheet or Database?