Replacement of etonogestrel implant(Implanon) is normally done after how many years?

Implanon is a single rod subdermal implant with 68 mg of the progestin etonogestrel (ENG), and an ethylene vinyl acetate copolymer cover. It can be used as contraception for 3 years and then replaced at the same site or opposite arm. It is placed in the medial surface of the upper arm 6 to 8 cm from the elbow in the biceps groove within 5 days of onset of menses. Prolonged and frequent bleeding is the most common adverse effect. Ref: Cunningham F.G., Leveno K.J., Bloom S.L., Hauth J.C., Rouse D.J., Spong C.Y. (2010). Chapter 32. Contraception.