VAG-COM Demo to Full Version Upgrade

Hello fellow mechanics!

I'm currently seriously considering purchasing a diagnostic system, now that I've decided to keep my vehicle for a few more years.
I have two questions, however:

'Does the demo version of VAG COM suffice for performing common measurements, test drives with data logging, and dynamic injection timing adjustments after timing belt replacement? Or, to put it another way, which IMPORTANT functions are only offered by the full version? This full version is a bit expensive for me... Or are there any affordable software options that offer a real alternative?'

'I have followed the intensive discussions about adapters here in the forum with great interest. Unfortunately, I don't have enough knowledge of electronics, and especially not the time to examine them in detail in order to attempt to reproduce an adapter. Which ready-made adapters can be recommended as relatively uncomplicated (motor as indicated in my signature), or does anyone have any of these adapters lying around?'

I am grateful for any advice .

Experience on the edge:

Recently, the relay 109 also failed in my car. The engine occasionally wouldn't start after being stopped at a railway crossing, and the glow plug symbol was inactive. Then, suddenly, while driving normally, the oil warning light came on with a beep. I pulled over to the right, checked everything, and it seemed okay, but the engine wouldn't start. It only started after repeatedly turning the key and fully disengaging the starter. Thanks to the forum - the search function on this forum is invaluable - I replaced the relay and, out of curiosity, took a look inside the old one. I think I saw a cold solder joint, which was a bit dull, and I think there was a crack in the solder joint.

Thank you very much for the helpful information, and please keep up the good work!!!