Wordfast Pro is installed on a local computer as described here.
To install and activate Wordfast Pro:
Wordfast Pro opens in Demo Mode.
To activate Wordfast Pro, a license must be obtained and registered either online or offline.
Wordfast Pro demo mode provides an opportunity to view and try out the functions with limitations.
With a non-licensed Wordfast Pro, you are limited to creating bilingual projects and storing up to 500 translation units in your Translation Memory.
Refer to:
Online Activation
Offline Activation