How often does the Adaxes Self-Service Client get updated
Softerra Adaxes releases twice a year. Thus, Adaxes Self-Service Client gets updates not more often than twice a year and only if new version of Adaxes gets changes related to Self Password Reset.
how do we update the workstations that it is already deployed on?
For testing purposes you can update Adaxes Self-Service Client manually. To do so, just run the new installation file on the computers which you want to update.
If the deployment was performed by GPO, you can just replace the installation file on the network share configured for the GPO with a new file. The installation will start automatically when a computer is restarted.
For additional information about Adaxes Self-Service Client, have a look at Adaxes Self-Service Client Installation Guide.