CAD File Converter 3.0
After installation CadFileConverter can be used for 15 consecutive days free-of-charge and without limitations.
On the fifteenth day, an activation code must be inserted to keep the program running.
Until activation, the following window appears on startup:

Windows Mac Os X
Pressing Continue allows you to continue using the program.
Pressing Cancel allows you to interrupt and exit the program.
Pressing Activate allows you to activate the program permanently, with no time limits. After pressing Activate the following window appears:

Windows Mac Os X
You must insert User and Code, which you can obtain from Interstudio on purchasing the user licence.