Verse 11 and 12, which is the context of 13 (which you ignored) is absolute.
These are present tense verbs! ... The one who has the Son ... has (present active indicative) life. Verse 13 uses the subjunctive because there is the possibility that there are those who do not have the Son, continuing the thought from verse 12!
and verse 13 makes sure that you realize that it is a possibility if you continue to have the Son.
Tell me where is Judas now?