Tomemorizelineswouldbetranslatedas"tomemorizedialogues"inEnglish.However,"tomemorizeascript"or"tolearnlines"mayalsobeuseddependingonthecontext.
To memorize lines would be translated as "to memorize dialogues" in English. However, "to memorize a script" or "to learn lines" may also be used depending on the context.