one's days are numbered
Some period of time, such as a term of employment or a lifetime, is coming to an end.
If his performance does not improve very soon, his days at this company are numbered.
ADJ.
easy, hard, long, many, overseas, slow, tired, younger
It took many days before we finally heard back from the company about our complaint.
VERB + DAYS
couple, mind, overworking, slept, travel, visit, work, works
I haven't slept properly in days and I'm completely exhausted now.
DAYS + NOUN
garage
We took the car to the days garage for its regular maintenance check.
PREP.
in
In the old days, people didn't have smartphones to check constantly.