In a word: no. While I am not in any sense an expert, my research into Myers-Briggs typology for the purpose of exploring personal style idiom has not turned up any expert saying that an individual may change type over a lifetime.
I have, however, turned up a couple of reasons why a person may have differing outcomes that make it appear that type has changed. Or just make the whole system seem confusing 😉
The most obvious reason for differing outcomes is the fact that each pair of letters is measuring a dichotomy of preference and most people are not extreme in any characteristic; therefore, depending on how each question strikes you on any given day, you may easily flip-flop back and forth between, for example, introvert and extravert.
The other reason I have turned up is that we grow. Officially called “type development”, we grow into all four functions – that is: sensing and intuition, thinking and feeling – in a predictable sequence. From the Myers-Briggs Foundation site:
As we grow and develop, the different functions develop. The timing of this development has been the subject of considerable study. It is generally believed that the dominant generally develops up to age 7, the auxiliary up to age 20, the tertiary in the 30s and 40s and the inferior or fourth function at midlife or later.
In my own life, the strongest evidence of this has been the interest in “doing things” that guided so much of my 30s and 40s. By “doing things”, I mean cooking, crafting, and other reality-based, task-type functions. My tertiary function is sensing. Unfortunately, I never got really good or fast at anything, although I am tolerably competent in the kitchen 😉
My conclusion? Your MBTI might be slightly more reliable when you are younger. Especially the two letters in the middle.