(one's) number is up American British phrase
used to say that someone is about to suffer, die or be punished.
You never know when your number's up, so just live the best life that you can!
OMG, I just broke my mom's favorite vase, my number's up.
When the ship started to sink, Ken thought that his number was up.
Luana: I got F for my final exam, my number is up. Liza: Learn by experience and study hard next time. Everything will be fine.
There is 'to be' in the phrase, therefore it needs to conjugate within the sentence. Besides, we should use this phrase in the appropriate context.
someone believe that they are allowed to do whatever they want in their own home
It is always advised that wherever you go, a man's home is his castle