You will never know if a VPN provider doesn't keep log. It's impossible, even if the provider is open source. A VPN provider can see all your traffic, just like your ISP, there is no difference.
Also, keep in my mind that VPN marketing is utterly misleading. First of all, hiding IP it's not so relevant, tracking technology are far more complicated. Using a technology called fingerprint websites and malicious actors can still be able to identify you.
VPN doesn't encrypt anything, for that there is HTTPS, which is already available for the 99% of sites. Therefore, VPN doesn't add any security.
Now, I'm jot saying that you should not using a VPN. it's up to your user case, threat model and trust.
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