Careful about doing this. Laptop and phones change networks. If my wifi is weak you'll see my phone switch to data intermittently. Forcing me to re-auth every switch would be painful. Some VPN providers also change IP addresses regularly (I've seen <1 minute between switches).
Also people in countries where the government censors the internet often use VPNs to bypass that censorship, so their IP address might change many times a day, including jumping to a different country. IP addresses should really not be used for anything beyond packet routing.
