diff --git a/src/accounting/signals.py b/src/accounting/signals.py
index c3bd259..4e90656 100644
--- a/src/accounting/signals.py
+++ b/src/accounting/signals.py
@@ -4,6 +4,8 @@ from django.conf import settings
 from django.core.mail import send_mail
 from django.db.models.signals import post_save
 from django.dispatch import receiver
+from django.utils import timezone
+from membership.models import Membership
 
 from . import models
 
@@ -19,3 +21,19 @@ def check_total_amount(sender: models.Payment, instance: models.Payment, **kwarg
             settings.DEFAULT_FROM_EMAIL,
             settings.ADMINS,
         )
+
+
+@receiver(post_save, sender=models.Payment)
+def mark_order_paid(sender: models.Payment, instance: models.Payment, **kwargs: dict) -> None:  # noqa: ARG001
+    """Mark an order as paid when payment is received."""
+    instance.order.is_paid = True
+    instance.order.save()
+
+
+@receiver(post_save, sender=models.Payment)
+def activate_membership(sender: models.Order, instance: models.Order, **kwargs: dict) -> None:  # noqa: ARG001
+    """Mark a membership as activated when its order is marked as paid."""
+    if instance.is_paid:
+        Membership.objects.filter(order=instance, activated=False, activated_on=None).update(
+            activated=True, activated_on=timezone.now()
+        )