With Get a Subscription By Id invocable action, you can get detail of existing Subscription in Stripe by providing few parameters.

• Create a new flow.
• Add logic to get Stripe Subscription Id from your Salesforce object like Contact.
  • If you don't have it in Salesforce then no problem, you can add Lite Pae's Get Subscriptions By Customer action in the flow to retrieve existing subscriptions for a customer in Stripe and then map Subscription Ids from its response to Salesforce.
• Add a step to query Payment Account and store its Id in a flow variable i.e. paymentRecordId.
• Add a new Action and search for Get a Subscription By Id.
  • Setup its required input values based on previous steps like paymentRecordId, Subscription Id.
  • You may want to handle its response as well to output variables by clicking on Advanced section of this node to know if it was processed successfully or not (Status). Specially, variables with Subscription or ResultInJSON for full subscription details in json format.
• You can add a screen component to show the response from previous step.
• Publish flow.
• Add this flow on your Salesforce Lightning page, Experience Cloud Site
  • Tip: You can create a Quick Action button to call this Flow and add it on your Object Layout for Example on Contact page layout.