It means to stay important. That phrase is not used often. The term "relevant" is used more frequently however.. Again, it just means something or someone is important to an issue. Yusuke's advice was relevant to our decision. In that sentence it means important. However, it can also mean something relates. For instance. Yusukee's testimony was relevant to the case. In that situation it may not be important, or it may be, but it relates to the topic.