If you have the transaction number, you can leave feedback as long as the transaction is active - often longer than 90 days.
Generally I've found items are "active" for up to 150 days, if you look at someone's feedback and look for the newest item numbers that are no longer highlighted, plug the item number into the search box and the page will still come up, when you leave feedback the associated item number will not be clickable, to many this will mean feedback can no longer be left but obviously this is not the case.
Another feedback trick, if you need more characters you can log into the ebay Taiwan site and leave feedback from there where you get about 20 more characters to play with. (at least this used to work).
Ben

"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915

"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915
- answering Trolls is voluntary, my policy is not to participate.