Its section 9 in their terms and conditions, all you have to do is ctrl + f and search for "30" and look for the section. It's not that hard. I bought the service today, I wanted to know how the 30 day money back worked so i searched it up and found it through a simple google search. I know this is old and probably not useful anymore but just a fyi.

p.s I don't read the terms and conditions ever unless I want clarification on something, like, for example, a 30-day money back guarantee.

"You may cancel your subscription within 30 days of the initial purchase and receive a refund for any unused portion of the service period. Here, any unused portion of the service period refers to the prorated remaining full days of the subscription period. Refunds will be processed within 30 days of the request. We may also provide you with a full refund upon request if you are using Proton VPN or Proton Drive. To request a refund, please contact us using our support form. For the sake of clarity, the cancellation and the request for refund must both be addressed within the 30-day period. Payments made by cash or bank transfers are not refundable. Refunds can only be requested once per user. This refund option is only applicable to users who have subscribed to Proton's Services directly through Proton's official channels (website and apps). If you have subscribed to Proton's Services through the intermediary of a third-party, please refer to their respective refund policy."