Acostumbraron comes from the verb acostumbrar, meaning 'to accustom' or 'to get used to'. It's a key word in this song because it describes how the singer's partner's actions have profoundly shaped his life.
He sings, "Y tus caricias que me acostumbraron a vivir contigo" (And your caresses that got me used to living with you). This highlights how deeply ingrained their presence became, making it impossible for him to forget them and showing the lasting impact of their love.
Neto Bernal's "Una Vez Más" is a heartfelt plea from someone who deeply misses a past love. He's so desperate that he'd be content with just seeing them "una vez más" [one more time], even offering his life for that single glimpse. He admits that the breakup is his fault, saying "Yo sé que tienes toda la razón y que la culpa es mía" [I know you are completely right and the fault is mine].
He can't forget anything about this person – their kisses, their beautiful face, and especially their caresses that made him used to living with them, "a soñar despierto, y a besar dormido" [dreaming awake, and kissing in his sleep]. Now, all he wants is to see them again, even if it's just for a moment. It's a really emotional song about longing and regret.