diff --git a/gui/packages/ubuntupro/lib/pages/subscribe_now/subscribe_now_model.dart b/gui/packages/ubuntupro/lib/pages/subscribe_now/subscribe_now_model.dart
index 3eaa362ea..3b0af038d 100644
--- a/gui/packages/ubuntupro/lib/pages/subscribe_now/subscribe_now_model.dart
+++ b/gui/packages/ubuntupro/lib/pages/subscribe_now/subscribe_now_model.dart
@@ -4,7 +4,6 @@ import 'package:flutter/foundation.dart';
 import 'package:p4w_ms_store/p4w_ms_store.dart';
 
 import '/core/agent_api_client.dart';
-import '/core/either_value_notifier.dart';
 import '/core/pro_token.dart';
 
 class SubscribeNowModel extends ChangeNotifier {
@@ -13,7 +12,7 @@ class SubscribeNowModel extends ChangeNotifier {
 
   final _token = ProTokenValue();
   ProTokenValue get token => _token;
-  bool get canSubmit => token.valueOrNull != null;
+  bool get canSubmit => token.token != null;
 
   /// Returns true if the environment variable 'UP4W_ALLOW_STORE_PURCHASE' has been set.
   /// Since this reading won't change during the app lifetime, even if the user changes
@@ -59,19 +58,23 @@ class SubscribeNowModel extends ChangeNotifier {
   }
 }
 
-/// A value-notifier for the [ProToken] with validation.
-class ProTokenValue extends EitherValueNotifier<TokenError, ProToken?> {
-  ProTokenValue() : super.err(TokenError.empty);
+/// A [ProToken] with validation.
+///
+/// Similar to a [EitherValueNotifier], without the [ValueNotifier].
+class ProTokenValue {
+  ProTokenValue() : either = const Either.left(TokenError.empty);
 
-  String? get token => valueOrNull?.value;
-
-  bool get hasError => value.isLeft;
+  Either<TokenError, ProToken?> either;
+  ProToken? get token => either.orNull();
+  String? get value => either.orNull()?.value;
+  TokenError? get error => either.fold(ifLeft: (e) => e, ifRight: (_) => null);
+  bool get hasError => either.isLeft;
 
   void update(String token) {
-    value = ProToken.create(token);
+    either = ProToken.create(token);
   }
 
   void clear() {
-    value = const Right<TokenError, ProToken?>(null);
+    either = const Either.right(null);
   }
 }
diff --git a/gui/packages/ubuntupro/lib/pages/subscribe_now/subscribe_now_page.dart b/gui/packages/ubuntupro/lib/pages/subscribe_now/subscribe_now_page.dart
index 24ec446fc..6de354f14 100644
--- a/gui/packages/ubuntupro/lib/pages/subscribe_now/subscribe_now_page.dart
+++ b/gui/packages/ubuntupro/lib/pages/subscribe_now/subscribe_now_page.dart
@@ -94,7 +94,7 @@ class SubscribeNowPage extends StatelessWidget {
   }
 
   void trySubmit(SubscribeNowModel model) {
-    model.applyProToken(model.token.valueOrNull!).then(onSubscriptionUpdate);
+    model.applyProToken(model.token.token!).then(onSubscriptionUpdate);
     model.token.clear();
     controller.clear();
   }
diff --git a/gui/packages/ubuntupro/lib/pages/subscribe_now/subscribe_now_widgets.dart b/gui/packages/ubuntupro/lib/pages/subscribe_now/subscribe_now_widgets.dart
index 2049b082c..311942a77 100644
--- a/gui/packages/ubuntupro/lib/pages/subscribe_now/subscribe_now_widgets.dart
+++ b/gui/packages/ubuntupro/lib/pages/subscribe_now/subscribe_now_widgets.dart
@@ -60,39 +60,29 @@ class _ProTokenInputFieldState extends State<ProTokenInputField> {
           styleSheet: linkStyle,
         ),
         const SizedBox(height: 8),
-        ValueListenableBuilder(
-          valueListenable: model.token,
-          builder: (context, _, __) => Row(
-            crossAxisAlignment: CrossAxisAlignment.start,
-            children: [
-              Expanded(
-                child: TextField(
-                  inputFormatters: [
-                    // This ignores all sorts of (Unicode) whitespaces (not only at the ends).
-                    FilteringTextInputFormatter.deny(RegExp(r'\s')),
-                  ],
-                  autofocus: false,
-                  controller: widget.controller,
-                  decoration: InputDecoration(
-                    label: Text(lang.tokenInputHint),
-                    error: model.token.errorOrNull?.localize(lang) != null
-                        ? Padding(
-                            padding: const EdgeInsets.only(top: 4),
-                            child: Text(
-                              model.token.errorOrNull!.localize(lang)!,
-                              style: theme.textTheme.bodySmall!.copyWith(
-                                color: YaruColors.of(context).error,
-                              ),
-                            ),
-                          )
-                        : null,
-                  ),
-                  onChanged: model.tokenUpdate,
-                  onSubmitted: (_) => widget.onSubmit?.call(),
-                ),
-              ),
-            ],
+        TextField(
+          inputFormatters: [
+            // This ignores all sorts of (Unicode) whitespaces (not only at the ends).
+            FilteringTextInputFormatter.deny(RegExp(r'\s')),
+          ],
+          autofocus: false,
+          controller: widget.controller,
+          decoration: InputDecoration(
+            label: Text(lang.tokenInputHint),
+            error: model.token.error?.localize(lang) != null
+                ? Padding(
+                    padding: const EdgeInsets.only(top: 4),
+                    child: Text(
+                      model.token.error!.localize(lang)!,
+                      style: theme.textTheme.bodySmall!.copyWith(
+                        color: YaruColors.of(context).error,
+                      ),
+                    ),
+                  )
+                : null,
           ),
+          onChanged: model.tokenUpdate,
+          onSubmitted: (_) => widget.onSubmit?.call(),
         ),
       ],
     );
diff --git a/gui/packages/ubuntupro/test/pages/subcribe_now/subscribe_now_widgets_test.dart b/gui/packages/ubuntupro/test/pages/subcribe_now/subscribe_now_widgets_test.dart
index 89dfa3ab5..dd67a73fe 100644
--- a/gui/packages/ubuntupro/test/pages/subcribe_now/subscribe_now_widgets_test.dart
+++ b/gui/packages/ubuntupro/test/pages/subcribe_now/subscribe_now_widgets_test.dart
@@ -34,11 +34,11 @@ void main() {
       final value = ProTokenValue();
 
       value.update('');
-      expect(value.errorOrNull, TokenError.empty);
+      expect(value.error, TokenError.empty);
 
       for (final token in tks.invalidTokens) {
         value.update(token);
-        expect(value.errorOrNull, TokenError.invalid);
+        expect(value.error, TokenError.invalid);
       }
     });
     test('accessors on success', () {
@@ -48,23 +48,11 @@ void main() {
       value.update(tks.good);
 
       expect(value.hasError, isFalse);
-      expect(value.errorOrNull, isNull);
-      expect(value.token, tks.good);
-      expect(value.valueOrNull!.value, tks.good);
-      expect(value.valueOrNull, tokenInstance);
-      expect(value.value, equals(ProToken.create(tks.good)));
-    });
-
-    test('notify listeners', () {
-      final value = ProTokenValue();
-      var notified = false;
-      value.addListener(() {
-        notified = true;
-      });
-
-      value.update(tks.good);
-
-      expect(notified, isTrue);
+      expect(value.error, isNull);
+      expect(value.value, tks.good);
+      expect(value.value, tks.good);
+      expect(value.token, tokenInstance);
+      expect(value.either, equals(ProToken.create(tks.good)));
     });
   });