feat(gdpr): add purpose for granting access to premium content

GDPR.txt

@@ -69,3 +69,15 @@ description:
     platforms (such as Apple Podcasts).
 mitigation:
     The e-mail can be generic.
+
+purpose: Grant access to premium content
+lawfulness: legitimate interest
+
+data: Subscriber's email address
+required: yes
+visibility: administrators
+description:
+    The subscriber's e-mail address is used to provide credentials for
+    listening to premium content.
+mitigation:
+    The e-mail can be generic.

public/.well-known/GDPR.yml

@@ -73,3 +73,14 @@ purposes:
           platforms (such as Apple Podcasts).
         mitigation: The e-mail can be generic.
         retention: forever
+  - description: Grant access to premium content
+    lawfulness: legitimate interest
+    data:
+      - field: Subscriber's email address
+        required: yes
+        visibility: administrators
+        description: |
+          The subscriber's e-mail address is used to provide credentials for
+          listening to premium content.
+        mitigation: The e-mail can be generic.
+        retention: until the subscription ends