No, I did not buy any auto calibration SW.
So on the Dev 1.0 level, there are multiple fixes to the distortion correction function. The way I understand it to work (once enabled ) is you use the bed height map tool ( in repetier-host tools) and that maps the distortion on the bed. Once completed, you save it in the EEPROM with a G command ( which is not currently our firmware. Then the firmware will automatically correct for the delta z for about the first 1 mm of layer height. see https://www.youtube.com/watch?v=L9URtv2LqKc
Here is the configuration utility words on it.
Attachment 11193