There is a GPS Module in Dishy, and they know where you are (Also if you have been good or bad, so be good for goodness sake).
In a Reddit AMA they were asked that, and more implied that the location may not work due to coverage issues, vs they will block it. But it is very early. This will almost certainly change as they deploy more and more customers.
I cannot figure out how to link to a specific Q/A. So here is the question from the AMA:
My question is regarding mobile use. I understand that currently the system is designed and optimized for use in a fixed location. However, I live on and work from my 47ft sailboat, currently tied, literally and figuratively, to a dock in South Florida. A mobile system that gives me reliable connectivity will truly set me free to roam the coastal US, Bahamas, and eventually beyond (once the inter-satellite laser link capability is ready). There's a lot of speculation as to whether the current hardware could handle a mobile platform using the phased array antenna and existing mechanical pointing capability, or whether more extensive active stabilization would be required. Anything you can share about this would be most welcome, including, especially, when mobile Starlink might be a reality.
And here is the answer:
Right now, we can only deliver service at the address you sign up with on starlink.com You might get lucky if you try to use Starlink in nearby locations, but service quality may be worse.
Mobility options - including moving your Starlink to different service addresses (or places that don't even have addresses!) - is coming once we are able to increase our coverage by launching more satellites & rolling out new software.