Should I use "in the" here?

Question

1. He played twenty days in the last season.
2. He played twenty days last season.

Last season is the last season in his career in this case. Are both sentences technically correct? Which one is better and why?

I'm not a native speaker and I'm a bit confused with this.

Answer 1

If you are talking about the last season of his career, you would say

He played twenty days in his last season.

If you are talking about the season before the current one, you would say

He played twenty days last season.
He played twenty days in the last season.

I would probably use the former, but the latter is perfectly correct and understandable.