"The last time was never" is a manner of saying that something has not occurred before.
The usual pattern for this sentence is "the last time was [time]", where we can insert any one of numerous indications of time, such as:
- The last time was five minutes ago.
- The last time was yesterday.
- The last time was at five p.m.
Although "never" is an indication of time, it is different from those above times which are somewhat like nouns; it functions more like an adverb.
For instance consider these, of which the first one is ungrammatical:
- It five minutes ago happened. *
- It happened five minutes ago.
And compare to these, where the second one is a borderline case: it is not outright ungrammatical but unusual.
- It never happened.
- It happened never. ?
"Five minutes ago happened" does not work because "five minutes ago" cannot function as an adverb. It follows the special grammar for indicating the time of an action, which follows the verb. However "never happened" is grammatical: "never" functions as an adverb modifying "happened".
"It happened never" follows a pattern whereby a clause introduces some element outside of the clause. We might write that with a colon: "It happened: never." This is similar to a structure like, "I know what I will order: a hamburger!" Similarly, "the last time was never" can be regarded as "the last time was: never".
Or possibly, "the last time was ... never", where the speaker begins to speak, then pauses to think and realizes that the event has never happened before, and utters the word "never". A longer version: "the last time was ... hmm, come to think of it, never! It has never happened before!".
The word never can function as a noun indicating time, when it is by itself. For instance it can be a curt, one-word answer to a question. All of these answers are correct:
- Q: When was the last time you went to Disneyland?
- A: Never.
- A: Just yesterday.
- A: Last year.
In "the last time was: never", the word functions in this way. The verb "was" is simply equating "last time" with a noun-like "never" just like "apple" and "red" are equated in "the apple was red".
The word "never" is not functioning as an adverb modifying was, which happens in a different kind of sentence like "there never was a last time, because it never happened before".