To keep, preserve, or maintain something in its current condition (transitive): to sustain, retain, or hold (e.g., maintain order, preserve quality or temperature).
室内の温度を一定に保つためにエアコンを使う。
I use the air conditioner to keep the room temperature constant.
会社は社員のモラルを保つことが重要だと考えている。
The company thinks it's important to maintain employee morale.
資料は湿気を避けて品質を保つように保管してください。
Please store the materials to avoid humidity so their quality is preserved.
To last, endure, or remain in good condition (intransitive): to be durable or keep well (e.g., food lasting, clothing wearing well).
このジャムは冷蔵庫で一ヶ月ほど保つ。
This jam will keep for about a month in the refrigerator.
この靴はよく保つから長く使えます。
These shoes are durable, so you can use them for a long time.
疲れがなかなか保たない日が続いている。
I've had days where I can't keep my energy up.