what is your zmodeler version? have you changed date on your computer recently? if you did, only online validation will work.
Here's a validation key for you: YFM-G2DE7-3VB5F, but I wish you configure browser or set up online validation, so you can do this on your own. Note, the very latest version of ZModeler has a settings->general->network->delay autoupdate => set to 3-5 seconds, so ZM will try to validate license before accessing updates server. it will work better this way.