Reva is an iPhone app that puts a pause in front of the apps you choose. Write to support@reva.otterwright.com and a person reads it.
Pauses stopped firing: this is nearly always the Screen Time permission, which iOS owns and which can be switched off without Reva being told. Settings inside the app has a button to ask for it again. A phone managed by someone else's Screen Time settings cannot be gated at all.
Billing: Apple handles it. Cancel from your Apple Account. Reva cannot issue refunds — only Apple can, through reportaproblem.apple.com.
Your data: export and deletion are both free and both in Settings inside the app. There is no account and no server holding your answers.
Reva is not a crisis service. findahelpline.com lists free helplines by country.