Poser phones home periodically, and if it's blocked for some reason, it will eventually stop working. This is supposedly an anti-piracy measure. I suspect they want you to have Poser connected to the web so they can sell you stuff from RMP through Poser.

A lot of people are very unhappy with this "feature." If you contact support, they may be able to extend the period between check-ins, but so far as I know, there is no longer any way to suspend this license check.