the Auto-Assist subscription only activates the automatic geo-fencing, without that you'll simply be asked if you want to activate geo-fencing once you leave your home-zone.
I think for questions like this it would be better to ask the manufacturer directly. Not sure if Galaxus knows the cost of the subscription.
https://www.tado.com/en...
The geofencing function is, as currently implemented rather useless.
It will turn off the heating if you leave the house. Once off you do not have the option to turn the heating on again. The heating will only turn on once you arrive home again, so pre-heating the house after an absence is not possible.