You have probably changed the date and ZModeler detected it as a cheating. I'm not sure whether this can be fixed, but you should try an "online validation" scheme - specify a password for your platform in account, then specify you account name and platform password in ZModeler.
When small dates span is detected as cheating I suggest to purchase a longer license, so it's validity period could cover a date span. You seems to have ~250 days of span detected, and it can't be covered even by the longest (2 year) license validation.
Unfortunately, I don't have any suitable solution in such a case. You can try creating a different user account, give it "Power user" permissions and try running ZModeler from another account on your OS.