He made sure that they would have enough food to______for so

last
够用,保持可用状态（一段时间） If something lasts
for a particular length of time,it continues to be able to be used for
that time,for example because there is some of it left or because it
is in good enough condition.
The repaired sail lasted less than 24 hours...
修好的帆支撑了不到24小时.
remain
保持;继续;持续 If someone or something remains in a particular state or condition,they stay in that state or condition and do not change.(保持某种状态不变)
The three men remained silent..这3个人保持着沉默.

其实，last在这里是“维持，持续，支撑”的意思。