When your ancestor was sentenced to Transportation for Life it did not mean that he or she was to spend the rest of their life in a penal colony. It meant they could never return to their native country such as Ireland. My ancestor John Moten was sentenced to life in Van Diemens Land or better known as Tasmania Australia for Life but would only have to serve 2 years 6 months confined to a Probation Station and then he was free to go anywhere he likes in Australia or any other colony as long as he never tried to go back to Ireland. Many think he did his time and vanished for some years when he actually worked at various jobs which I have managed to find before heading for Victoria.
Thanks Aussie John