。
Please insure it.
Literal
Insurance [obj-を] put-on please (polite).
保険をかける ('put on insurance') is the standard idiom for 'to insure.' かける has many idioms — 電話をかける (make a call), 迷惑をかける (cause trouble), 時間をかける (take time) — here the 'apply' sense. ~てください closes as a polite request.