How to Create a days left / days span for Certification expired date?

[adhaputraa]

Hello, can anyone provide me with some help?

I have a data about certification and I'm going to create a days left which is it depend on expired date.

And it updated every day so I can send some notification when it's already 7 days left. To extend the certification.

Thank you

I also have a row data like certification date, expired date and days left.