My eye doctor told me that you can only have laser eye surgery once. is this true?

LASIK enhancement: No, that isn't true. Is this doctor an optometrist or an md/surgeon? You can potentially get an enhancement if needed later on. The eye would need to be well healed, the refraction stable, sufficient corneal bed remaining, and the rest of the exam otherwise normal and healthy. But it is expected that a few percent of patients may need an enhancement as they may heal too under/overcorrected.