billing: Mention how the licenses are managed in /billing.

corporate/tests/test_stripe.py

@@ -487,6 +487,7 @@ class StripeTest(StripeTestCase):
         for substring in [
                 'Zulip Standard', str(self.seat_count),
                 'You are using', f'{self.seat_count} of {self.seat_count} licenses',
+                'Licenses are automatically managed by Zulip; when you add',
                 'Your plan will renew on', 'January 2, 2013', f'${80 * self.seat_count}.00',
                 'Visa ending in 4242',
                 'Update card']:
@@ -571,6 +572,7 @@ class StripeTest(StripeTestCase):
         for substring in [
                 'Zulip Standard', str(123),
                 'You are using', f'{self.seat_count} of {123} licenses',
+                'Licenses are manually managed. You will not be able to add ',
                 'Your plan will renew on', 'January 2, 2013', '$9,840.00',  # 9840 = 80 * 123
                 'Billed by invoice']:
             self.assert_in_response(substring, response)

corporate/views.py

@@ -225,6 +225,7 @@ def billing_home(request: HttpRequest) -> HttpResponse:
                 'has_active_plan': True,
                 'free_trial': free_trial,
                 'downgrade_at_end_of_cycle': downgrade_at_end_of_cycle,
+                'automanage_licenses': plan.automanage_licenses,
                 'licenses': licenses,
                 'licenses_used': licenses_used,
                 'renewal_date': renewal_date,

templates/corporate/billing.html

@@ -34,7 +34,16 @@
                         {% else %}
                         <p>Your current plan is <strong>{{ plan_name }}</strong>.</p>
                         {% endif %}
-                        <p>You are using <strong>{{ licenses_used }} of {{ licenses }} licenses</strong>.</p>
+                        <p>
+                            You are using <strong>{{ licenses_used }} of {{ licenses }} licenses</strong>.
+                            {% if automanage_licenses %}
+                            Licenses are automatically managed by Zulip; when you add or deactivate a user, the number of
+                            licenses will be immediately updated to reflect your new usage.
+                            {% else %}
+                            Licenses are manually managed. You will not be able to add new users to your organization once
+                            you are using all of your licenses.
+                            {% endif %}
+                        </p>
                         <p>
                             {% if renewal_amount %}
                                 {% if free_trial %}