You are right, the about dialog shows that my license expires 2010-05-11. Damn! Should have noticed this before.
Dear customer, thank you for contacting our support. As you have a Navicore license it should be perpetual. However please note that user's who had purchased a Wayfinder Navigator for Internet Tablets license have on a time based license. These licenses will expire. I have however extended your license so that it will not expire.