A lens cleaner is almost certainly unnecessary as CD/DVD and rewriter drives are completely sealed apart from when the tray is opened or closed.
If the Memorex was given to you as part of a working PC it could well be that the Nero software was a dedicated version for your particular Memorex rewriter.
If this is the case and you have transferred the rewriter to another system, you will need to first obtain/reinstall the original Nero software. It would then be worthwhile updating it from ahead's website.
However, looking at Memorex's website, the burning software that's favoured seems to be Easy CD Creater.