Not for a Kindle ebook: Amazon gives it its own number. For a paperback or hardcover you need an ISBN, and KDP will give you one free. You can use your own instead if you want your imprint listed as the publisher.
Free vs your own
A free KDP ISBN lists 'Independently published' and can only be used on KDP. Your own ISBN lists your imprint and works anywhere.
One per format
Paperback and hardcover each need their own ISBN.
KDP's rules change from time to time. Check KDP's own help pages for the current requirements before you publish.