License verification is controlled by Google servers, and the issue usually clears on its own within 24-48 hrs.
As an immediate solution I believe the license verification can only fail if the app can not contact the Google servers. So, if you turn off Wi-Fi (and maybe you have to turn off data too), SkySafari will not try to contact the servers and should run fine.
Please try this and let us know if this works for you.
