Pretty simple, all you have to do is set a persistent cookie with a trackable value (eg, session id or client id etc etc) on the client machine longer than a single broswer session. Create a table to hold key-value paris for this "ID". When the customer returns you will be able to read this cookie, retrieve the "ID" and search in the table for the key-value pairs against this "ID". That's it you have the remember me concept.
good luck!