There is a 13% chance that they actually do remember you, and they say "Of course! Star Wars Convention 02, right?!"
The other 87% of the time, that person has NO clue who you are, and you've just created a highly uncomfortable situation for you and for them. If you have to ask someone if they remember you, they're probably not one of your closest pals. I wouldn't go up to my best friend and say "Hey, remember me?" unless there was a blunt head trauma involved. The SECOND that question leaves your mouth, their head is racing through all 543 of their Facebook friends, hoping your face clicks into place. Chances are, it won't, and now they're put in the awkward position of saying "NOPE!", and now you feel like a dumb ass because you assumed they did.
Instead, my advice is just to ignore that person. Conversation is for friendly people.