Well, within the tolerance of the phase lock. If that wasn't literally perfect, or somehow constantly realigned by a phase alignment field traveling with it, the coherent waves would eventually separate into a disbursed, spreading vector pattern and just... dissipate. That's the flaw in the SciFi idea of sending information across space with lasers - space is really, REALLY big, and provides plenty of distance for a nice tight beam to turn into a suffused, random, dim, meaningless glow.
A lot more than a walk to the chemist, that’s peanuts compared to space.