If i use music that is not resignation in youtube Content id, and if the owner registers it content id after one year. Will i get strike?
You will not get a strike. But you will get a copyright claim. You could then clear the claim with your license.
However, if the music is advertised as being not registered with ContentID, there is a possibility that it gets claimed by fraudulent claimers, in which case the actual author will have to regain ownership before you can clear the claim. This is why it’s always safer to go with ContentID registered music, because you won’t run into such issues, and you won’t have to worry about clearing claims in the future, you’ll be able to do it right away.