〜ておく
do in advance; leave as is
Verb て-form + おく (casual: 〜とく / 〜どく)
Sign up free to review this point on a spaced schedule.
て-form + おく means doing something now so it's ready for later: 旅行の前にホテルを予約しておきます, "I'll book the hotel before the trip". It's preparation.
It also means leaving something in a state on purpose: 窓は開けておいてください, "please leave the window open".
In speech ておく shrinks to とく (でおく to どく): やっとく, "I'll take care of it"; 読んどいて, "read it beforehand, okay?"
It's the natural thing to say about getting ready: for a trip, a test, guests. 覚えておきます is "I'll make sure to remember that".
Examples
旅行の前にホテルを予約しておきます。
I'll book the hotel before the trip.
飲み物を冷蔵庫に入れておいてください。
Please put the drinks in the fridge so they're ready.
暑いから、窓は開けておいてください。
It's hot, so please leave the window open.
明日のテストのために、単語を覚えておきます。
I'll memorise the vocabulary for tomorrow's test.
大丈夫、私がやっとくよ。
Don't worry, I'll take care of it.