What about opening the package containing the contacts lens and then you seldom use it within a month, e.g. 10 or less times use, will it still be useable after the expected usage duration of just throw it away? I happen to ask a friend of mine who wore contacts for five years now and he told me if the contacts is rarely used within a month, an additional extended day can be used. I'm also confused. Can anyone clarify this?

My answer to my question:
Ok, I was browsing through the forum and found out this interesting topic "If You Don't Stop You'll Go Blind" and all the information I needed is there. So to answer my question, Do Not use it beyond the expiry date.