Why is registration info not linked to the account?

I’m a bit confused by the design of all this. I often reinstall avast! because i test loads of AV’s and every time i install avast! i have to re-register so that free license starts from scratch. If i just login to account directly, it does NOTHING. I’m logged in but it’s still nagging to register.
If i register, that should become tied to the active account for that instalaltion and every time i log in to avast! Account, it should also automatically take the license from it for as long as it’s valid. Otherwise, what’s the point of the extra account if it doesn’t really do much (especially about licenses)?