

このケーキ、お姉ちゃんの分もとっておくね。
レシートは念のためとっておいてください。
古い雑誌はとっておかないで、捨ててしまいました。
"とっておく" is in the lesson "Verbs 4" (Level 6), along with 13 other useful words. LinDuo has 180 topic lessons like this one, 2,379 words in total. Every word has an illustration, a transcription and pronunciation in a female and a male voice. Just 10–15 minutes a day is enough to learn them all. Free, and works offline.