Yes you can read and clear fault codes. However in the free shareware mode, the description of the fault may not be present and will be replaced with the message, "Shareware Version. To Decode all DTCs - Please Register/Activate". However, the DTC number will always be shown and the DTC can be cleared.
As to checking how the engine is running, you can monitor some live measuring values in the first 25 groups of measuring values. Beyond group 25 (there are up to 255 groups with 4 values per group) you must register the shareware.
Basic Settings, Adaptions, Output tests, Coding modules and so on are all restricted to the registered version.