billing: Allow to exclude realms from license limit check.

corporate/lib/registration.py

@@ -71,12 +71,10 @@ def send_user_unable_to_signup_message_to_signup_notification_stream(
 def check_spare_licenses_available_for_adding_new_users(
     realm: Realm, number_of_users_to_add: int
 ) -> None:
-    if realm.string_id in settings.LICENSE_CHECK_EXEMPTED_REALMS_ON_MANUAL_PLAN:
-        return  # nocoverage
-
     plan = get_current_plan_by_realm(realm)
-    if plan is None or plan.automanage_licenses:
+    if plan is None or plan.automanage_licenses or plan.exempt_from_from_license_number_check:
         return
+
     if plan.licenses() < get_latest_seat_count(realm) + number_of_users_to_add:
         raise LicenseLimitError()
 

corporate/migrations/0010_customerplan_exempt_from_from_license_number_check.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.2 on 2021-06-08 08:57
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("corporate", "0009_customer_sponsorship_pending"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="customerplan",
+            name="exempt_from_from_license_number_check",
+            field=models.BooleanField(default=False),
+        ),
+    ]

corporate/models.py

@@ -45,6 +45,10 @@ class CustomerPlan(models.Model):
     automanage_licenses: bool = models.BooleanField(default=False)
     charge_automatically: bool = models.BooleanField(default=False)
 
+    # Some non-profit organizations on manual license management pay only for their paid employees.
+    # We don't prevent these organizations from adding more users than the number of licenses they purchased.
+    exempt_from_from_license_number_check: bool = models.BooleanField(default=False)
+
     # Both of these are in cents. Exactly one of price_per_license or
     # fixed_price should be set. fixed_price is only for manual deals, and
     # can't be set via the self-serve billing system.