VPN purchase necessary while travelling to Mexico?

You probably do not need such a thing unless you're in a profession or situation where there's a high likelihood that someone would be tracking you and trying to intercept your communications. Very few people, relatively speaking, would fall into that category. I would, however, suggest that you avoid accessing bank accounts or other financial services unless absolutely necessary, particularly if you plan to be using Wi-Fi for data rather than your iPhone's cell connection. While the likelihood is small, there is always the chance that some bad actor could be scanning such Wi-Fi networks trying to capture data. Any responsible financial institution will be using encryption on their connections, but you never know. And of course you never want to put such information into an email or standard text message; those are never secure.

Regards.

There are really only 2 reasons that I can think of to purchase a VPN

1) Your company requires VPN to connect to their servers

2) Your school requires VPN for the same reason