PIN is a pro feature

app/src/main/java/eu/faircode/email/ActivitySetup.java

@@ -872,7 +872,7 @@ public class ActivitySetup extends ActivityBase implements FragmentManager.OnBac
                         if ("pro".equals(key) && !BuildConfig.DEBUG)
                             continue;
 
-                        if ("biometrics".equals(key) && !Helper.canAuthenticate(context))
+                        if ("biometrics".equals(key) || "pin".equals(key))
                             continue;
 
                         if ("alert_once".equals(key))

app/src/main/java/eu/faircode/email/FragmentOptionsPrivacy.java

@@ -246,8 +246,13 @@ public class FragmentOptionsPrivacy extends FragmentBase implements SharedPrefer
                             SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getContext());
                             if (TextUtils.isEmpty(pin))
                                 prefs.edit().remove("pin").apply();
-                            else
+                            else {
-                                prefs.edit().putString("pin", pin).apply();
+                                boolean pro = ActivityBilling.isPro(getContext());
+                                if (pro)
+                                    prefs.edit().putString("pin", pin).apply();
+                                else
+                                    startActivity(new Intent(getContext(), ActivityBilling.class));
+                            }
                         }
                     })
                     .setNegativeButton(android.R.string.cancel, null)