What it comes down to is that there are lots of different ways to get into a lounge. If you mean accessing it as a privilege of your Star Alliance status, the answer is "no" as posted because you need to have a Star Alliance flight departing on that day - and they will check your boarding pass. That doesn't mean you don't have another way to get in, such as membership in a Star Alliance lounge program, the right credit card, or something else. You should look up the options and see if you qualify for any of them.