In my case (not a tesla): software updates are only installed iff there is a recall notice. One time they installed an update because they had to wait anyways but that was not guaranteed and a service from the mechanic.
Most internet uses in cars (if not all) are bound the a person, not a car. Selling it most likely voids that subscription. In my case the uses are free for 5 years for the first buyer and a paid subscription afterwards. Most likely tesla does something similar.
Supercharging: See internet. Though I see plenty of them advertised with it. Maybe this is different in the EU.
Features (as in, bought features in feature packs or options) on the other hand are something of value (even if only software) added to the car and cannot be taken away without compensation or reimbursement. Unless you had a subscription but that is not the case in this instance.