Autocom original diagnostic interface tester purchase

Hello!
I need help with the topic, is it worth buying the original used autocom cdp tester?
There are a few on Allegro and olx only that some besides the autocom cdp wireless LAN inscription have a single letter stuck on them, I have already met A, B and C. Anyone know what this letter means? I would like to buy good equipment, so please give me a hint.
There are plenty of Chinese replacements, but there are different opinions and apparently they can be treated more as a toy. Is this true

The letters were stuck in workshops to which several items were purchased working under one license within one network.

Thanks for the information. The auction is just ending today at http://allegro.pl/interfejs-tester-diagnostyczny-autocom-oryginal-i6675524032.html
I'm wondering how much you can give the maximum for it?

Added after 1 [hours] 36 [minutes]:

I wonder one more thing how it is with the license, you have to buy it every year? What happens if I don't buy it, the program stops working?

Hello. The license is optional. The program will work, there will be no hints, diagrams.