i'd had reson enough in the last few months.

1.last为形容词,意思是“刚过去的/最近的”.
2.此结构中的few其实是a few“一些”,只不过因为前面有了the和last,所以a必须省略.
3.“in/during/over + the last/past + some time”是固定结构,意思是“在过去的一段时间内”.
4.此类a few省略成few的用法再如：every few hours“每隔几个小时”