In Modern Greek, it would be, “ἐχω ζωή”. But you probably meant it to be Biblical Greek, in which case you need the final Nu on the feminine accusative, so it is “ἐχω ζωήν”. But in that case, you really should be using the traditional diacritical marks, including the smooth breathing on the Epsilon, and acute and grave accents (depending on whether or not you mean the sentence to end with ζωήν.