If you remember, I live in London.
I live in London, if you remember. Both of those work for me. I agree with Lucy about the comma. It has to be there as otherwise 'if you remember' might be interpreted as a real condition for my living in London. I live in London if you remember. - So if I don't remember [what?] you do not live in London, huh?
I agree with this comment by Boozer, which applies to both versions of the sentence, with or without a comma (and the comma is needed). It just doesn't make sense, even though people may say it; the lack of logic is somehow ignored.