They should require essentially zero maintenance except maybe cleaning out all the dust/lint/crumbs/etc. that fall in between the keys. The actual key switches should last like... 20 years or more. What switches in your Coolermaster? I have a Coolermaster Masterkeys Pro S (Cherry MX Brown switches) and have used it for like 7+ years with no problems, all keys 100%-responsive and no double-actuations that I've ever observed.