We are unable to issue a refund for subscriptions made through the Google Play Store.
However, if the subscriber can demonstrate that the product (or service) was not usable or available during the subscription period, and the issue was not resolved after trying troubleshooting steps recommended by VPN Proxy Master. VPN Proxy Master may provide the Subscriber with a pro-rata refund of service fees paid at its sole discretion.
Alternatively, please check this Google Play support article about getting a subscription refund from Google Play - https://support.google.com/googleplay/answer/2479637#policy .