"It'll be nice not to have to use my fake IDs anymore"

Phil Mickelson's quote recommends that he has been using phony IDs in the past, and is now looking forward to the time when he no longer has to do so. This could be translated in a couple of various ways. To start with, it could be that he is looking forward to the time when he is no longer underage and can lawfully purchase alcohol or go into particular establishments. Additionally, it could be that he has been utilizing phony IDs for some other function, such as to gain access to limited locations or to purchase products that he would not otherwise be able to. Whatever the case, it is clear that he is anticipating the time when he no longer needs to rely on phony IDs. This could be analyzed as a sign of maturity, as he is eagerly anticipating the time when he can do things legally and without having to resort to using fake IDs.