Q: Imac 2012 late - os X El Capitan  - no imovie and iLife

Is your Mac a second-hand one? If so, iLife and iWork apps may be linked to the old owner's Apple ID, so you are not able to install them again without paying for them.

If not, maybe those apps are hidden in your Apple ID, so follow these steps to unhide them -> Hide and unhide purchases in the Mac App Store - Apple Support Then, go to Purchases and download them. If nothing works, contact with the Mac App Store support team -> http://www.apple.com/support/mac/app-store/contact

Those applications are not part of OS X. They are licensed to the original owner of the machine and the licenses for those are not transferrable. If you purchased the machine second hand, you will have to purchase them if you want them.

You are right, but you need to get in touch with the owner. If you can do this, there's a way to link the iMac to your Apple ID by deauthorizing it from the owner's ID, so you can reinstall those apps and OS X using your account. Have a look at this article -> What to do before selling or giving away your Mac - Apple Support