expression, noun which may take the genitive case particle 'no'
Refers to the period from the past up to the present moment. Often used as an adverbial phrase.
これまでにない経験をした。
I had an experience like never before.
So far, no problems have occurred.
expression
that's enough (for today); it ends here
Used to declare that something is finished or sufficient, often in a conclusive or dismissive tone. Common in spoken Japanese.
これまで！今日の練習は終わりです。
That's it! Today's practice is over.
もうこれまでだ。諦めよう。
This is the end. Let's give up.