if you own a car, you own it forever and without limits.
No you don't; the car must be titled, road-legal, emissions tested, insured, and you must be licensed to drive. Those are some of the limits on owning and using a car. Physical possession doesn't constitute a natural right.
More generally, you shouldn't pretend like you can divine human law from physical constraints. Human law serves humans. Property law serves humans. Laws might want to take into account the nature of intellectual property as bits, or they might not, depending on what is practical and desirable; but the bits are an implementation detail.
I'm pretty sure you need a license to own a car in most jurisdictions, but that's not the point. (And you definitely need a title to own a car because that's how you own a car. In some jurisdictions merely possessing the physical copy of the title implies ownership of the car, which is why you always keep the title in a safe place.)
Actually, you made my point for me. The point is society limits the way people can use property for practical reasons. There's no reason you can't do that on intellectual property because "omg it's made of bits".
The title is one way to recognize the rightful owner. If the title is destroyed or missing, those who believe in natural rights would still recognize ownership. Those who believe in state-given rights might not.
Also, you mentioned earlier that mere possession does not imply rightful ownership. I totally agree, as would anyone who has been the victim of theft.
No you don't; the car must be titled, road-legal, emissions tested, insured, and you must be licensed to drive. Those are some of the limits on owning and using a car. Physical possession doesn't constitute a natural right.
More generally, you shouldn't pretend like you can divine human law from physical constraints. Human law serves humans. Property law serves humans. Laws might want to take into account the nature of intellectual property as bits, or they might not, depending on what is practical and desirable; but the bits are an implementation detail.