In Parshat Tetzave (Shmot 27:20-21), after the building of the Mishkan (Tabernacle) was complete, B’nai Yisrael were commanded regarding the oil that would be used for the Ner Tamid (eternal lamp):
Now you shall command B’nai Yisrael that they shall take for you pure, pressed olive oil for illumination, to kindle the lamp continually. In Ohel Moed (the Tent of Meeting), outside the partition that is near the Testimonial-tablets, Aaron and his sons shall arrange it from evening until morning, before God, an eternal decree for their generations, from B’nai Yisrael.
Sforno explains that as opposed to the other gifts that were given to the Mishkan which were one time contributions to help get the Mishkan set up, the donation of olive oil would be ongoing. It would constantly need to be replaced.
The olive oil that was used in the desert was from the reserves that B’nai Yisrael brought out of Egypt as there were no olive trees available in the wilderness.
Upon arriving in the Land of Israel, they would have the luxury to systematically make new olive oil.
In Parshat Beha’alotcha (Bamidbar 8:1-3), once the Mishkan was dedicated on the 1st of Nisan, Aaron was commanded in regards to the Menorah:
God spoke to Moshe, saying, “Speak to Aaron and say to him: When you kindle the lamps, toward the face of the Menorah shall the seven lamps cast light.” Aaron did so; toward the face of the Menorah he kindled its lamps, as God had commanded Moshe.
According to Rashbam, since the lighting of the Menorah is a procedure that is repeated daily it is mentioned here. Even though the Mishkan had been completed and all of the work had been done, the Menorah was incomplete as the oil and wicks needed to be renewed regularly and the lighting of the flame was required as a continuing procedure on a daily basis.
The Menorah was part of an ongoing partnership between B’nai Yisrael who brought the oil and Aaron and his sons (the Kohanim) who lit it. By working together they were able to bring light into the world.