Download the current trial version here at no cost.
The trial version runs for 30 days and is not limited in regards to functions.

On-Screen Keyboard/Text communication software

Multilingual On-Screen Keyboard/Text Communication Software
For Windows 10®, Windows 8®, Windows 7®, Windows Vista® and Windows XP®

[Download OnScreenKeys]
Version 7.0.90, 148 mb

Scanning software

Mouse Scanning Software can be used as a scan module in combination with OnScreenKeys, but is capable of running independently as well.
For Windows XP®, Windows Vista®, Windows 7® and Windows 8®.

[Download OnScreenScan]
Version 1.0.45, 4 mb