Approximately 40 years. His approximate age when he had the experience at Mt Sinai and received the Ten Commandments was in his early 80s. At 120 according to other sources he climbed to the top of Mt. Nebo, saw the promised land and died. So, it would be exactly forty years if he was exactly 80 when he received the tablets. But it would be slightly fewer years if he was in his early 80s. Best estimation 35-40 years.
The commandments were all given in Moses' life, but their application stretches all the way to the present.
Moses Beregovsky died in 1961.
Moses the Black died in 405.
Moses Galante died in 1806.
Moses Stuart died in 1852.
Moses Tyson died in 1969.
Bessie Moses died in 1965.
Moses Kinkaid died in 1922.
Moses Wight died in 1895.
Charles Moses died in 1988.
Moses Bowness died in 1894.
Moses Coady died in 1957.