ProtonVPN

Proton VPN is owned by ProtonMail, a secure email service that offers encrypted email. Proton has been around for many years and their secure email is very good. The VPN is safe, secure and centred around privacy. Proton VPN is the only VPN that offers a real and secure VPN absolutely free. The free version isn't really limited but only has three locations available from the thousands that are available to paying customers. Those three locations are usually loaded to near capacity, so you won't get super speeds them. Also the three free locations don't unblock geo-restricted content all the time. It's touch and go. Getting ProtonVPN is free and anonymous. Just get a free ProtonMail email address and you get the VPN for free. You can pay for an upgraded VPN and have access to more locations and servers. Crypto currency is accepted for even more privacy. Take note, ProtonVPN is a bit pricey for what you get. I recommend paying with crypto currency as there is no conversion fee. If you live in the UK, your money will need to be converted to USD or Euros. Either way, you'll pay a fee for the currency conversion. Both PayPal and your Bank will charge you a fee AND take a percentage of the conversion.
No, i don't have proof of purchase. How would I get proof of purchase for something that's free?

I remember that one site that detects VPNs and proxies and I put Proton VPN in stealth mode and I didn't get detected. (I can't show proof of purchase because I use the free version.)

ProtonVPN is a great VPN for anybody who cares about privacy and security I love it and have been using it since April 2019 and have had no problems since.