If you have used it as a trial before, you must completely remove it and delete all registry entries under the name of Topaz Labs. This is important, because once a trial account signed in, it writes to registry and day count starts. This pre-fixed copy can work fully offline, no need to sign in with any account.
– Just install and use. Block it using a firewall. There’s no need for active internet to use it. Just block connections with firewall or use offline.