Johns Gospel has a total of seven I ams.
John 10:9-I am the door.
John 15:1-I am the true vine.
John 8:12-I am the light of the world.
John 10:11-I am the good shepherd.
John 11:25-I am the resurrection and the life.
John 14:6-I am the way, the truth, and the life.
John 6:48-I am the bread of life.
All seven of these I am sayings are figures of speech. Jesus is referring to the spiritual hunger in man for salvation. He promises to everyone who will come to him that he will satisfy their spiritual hunger for salvation forever. Likewise, we also drink to satisfy thirst. A one time coming to Jesus and believing on Jesus will satisfy mans spiritual need of salvation forever. This is accomplished by grace through faith alone.
Conversion is ongoing, and not one time only.