diff --git a/firestore-stripe-payments/README.md b/firestore-stripe-payments/README.md
index babfff02..e9bf11af 100644
--- a/firestore-stripe-payments/README.md
+++ b/firestore-stripe-payments/README.md
@@ -60,6 +60,49 @@ Then, in the [Stripe Dashboard](https://dashboard.stripe.com):
 
 - Create a new [restricted key](https://stripe.com/docs/keys#limit-access) with write access for the "Customers", "Checkout Sessions" and "Customer portal" resources, and read-only access for the "Subscriptions" and "Prices" resources.
 
+#### Installing via Firebase CLI 
+
+When installing via the CLI, be sure to pin the version. 
+
+```
+firebase ext:install invertase/firestore-stripe-payments --project=projectId_or_alias
+Alternatively for local source:
+firebase ext:install . --project=projectId_or_alias
+```
+
+The current version can be found in [extension.yaml](extension.yaml). 
+
+#### Using webhooks locally
+
+If you wish to test the webhooks **locally**, use the following command to configure the extension:
+
+```
+firebase ext:configure firestore-stripe-payments --local
+```
+
+Be sure to configure your test mode [API Key](https://stripe.com/docs/keys) and webhook [signing secret](https://stripe.com/docs/webhooks/signatures#:~:text=Before%20you%20can%20verify%20signatures,secret%20key%20for%20each%20endpoint.) when prompted. 
+
+Start the firebase emulator with:
+
+```
+firebase emulators:start --project=projectId_or_alias
+```
+
+Find the functions path associated with the stripe extension, typically it looks like this:
+
+- `http://192.0.0.1:5001/{projectId}/{region}/ext-firestore-stripe-payments-handleWebhookEvents`
+
+- You can tunnel your local endpoint using a tool like [ngrok](https://ngrok.com/). In this case you will tunnel the localhost domain and port `http://127.0.01:5001`. Replace `127.0.0.1:5001` with your tunnel url. The end result would look something like:
+
+```
+https://1234-1234-1234.ngrok.io/{projectId}/{region}/ext-firestore-stripe-payments-handleWebhookEvents
+```
+
+- Configure your test mode stripe [webhook endpoint](https://stripe.com/docs/webhooks) with the url you just constructed. 
+
+- Your local webhooks are now set up. 
+
+
 #### Billing
 
 This extension uses the following Firebase services which may have associated charges:
diff --git a/firestore-stripe-payments/functions/__tests__/tests/checkoutsessions/createCheckoutSession.test.ts b/firestore-stripe-payments/functions/__tests__/tests/checkoutsessions/createCheckoutSession.test.ts
index 6a928b4a..546406da 100644
--- a/firestore-stripe-payments/functions/__tests__/tests/checkoutsessions/createCheckoutSession.test.ts
+++ b/firestore-stripe-payments/functions/__tests__/tests/checkoutsessions/createCheckoutSession.test.ts
@@ -66,6 +66,52 @@ describe('createCheckoutSession', () => {
       expect(success_url).toBe('http://test.com/success');
     });
 
+    test('should setup a future payment with mode:setup', async () => {
+      const collection = firestore.collection('customers');
+
+      const customer: DocumentData = await waitForDocumentToExistInCollection(
+        collection,
+        'email',
+        user.email
+      );
+
+      /** Define params */
+      const client = 'web';
+      const mode = 'setup';
+      const success_url = 'http://test.com/success';
+      const cancel_url = 'http://test.com/cancel';
+      const payment_method_types = ['card'];
+
+      const checkoutSessionCollection = collection
+        .doc(customer.doc.id)
+        .collection('checkout_sessions');
+
+      const checkoutSessionDocument: DocumentReference =
+        await checkoutSessionCollection.add({
+          client: 'web',
+          mode: 'setup',
+          success_url: 'http://test.com/success',
+          cancel_url: 'http://test.com/cancel',
+          payment_method_types,
+        });
+
+      const customerDoc = await waitForDocumentToExistWithField(
+        checkoutSessionDocument,
+        'created'
+      );
+
+      const result = customerDoc.data();
+
+      expect(result.client).toBe(client);
+      expect(result.mode).toBe(mode);
+      expect(result.success_url).toBe(success_url);
+      expect(result.cancel_url).toBe(cancel_url);
+      expect(result.payment_method_types).toEqual(payment_method_types);
+      expect(result.sessionId).toBeDefined();
+      expect(url).toBeDefined();
+      expect(result.created).toBeDefined();
+    });
+
     test.skip('throws an error when success_url has not been provided', async () => {});
 
     test.skip('throws an error when cancel_url has not been provided', async () => {});
diff --git a/firestore-stripe-payments/functions/src/index.ts b/firestore-stripe-payments/functions/src/index.ts
index ed5e451b..2cb5052b 100644
--- a/firestore-stripe-payments/functions/src/index.ts
+++ b/firestore-stripe-payments/functions/src/index.ts
@@ -104,6 +104,26 @@ exports.createCustomer = functions.auth
     });
   });
 
+function generateLineItems(
+  line_items: Stripe.Checkout.SessionCreateParams.LineItem[],
+  price: string,
+  quantity: number
+): Stripe.Checkout.SessionCreateParams.LineItem[] {
+  if (line_items) {
+    return line_items;
+  }
+
+  if (price && quantity)
+    return [
+      {
+        price,
+        quantity,
+      },
+    ];
+
+  return [];
+}
+
 /**
  * Create a CheckoutSession or PaymentIntent based on which client is being used.
  */
@@ -185,14 +205,7 @@ exports.createCheckoutSession = functions
           shipping_rates,
           customer,
           customer_update,
-          line_items: line_items
-            ? line_items
-            : [
-                {
-                  price,
-                  quantity,
-                },
-              ],
+          line_items: generateLineItems(line_items, price, quantity),
           mode,
           success_url,
           cancel_url,
@@ -205,6 +218,7 @@ exports.createCheckoutSession = functions
         if (payment_method_types) {
           sessionCreateParams.payment_method_types = payment_method_types;
         }
+
         if (mode === 'subscription') {
           sessionCreateParams.payment_method_collection =
             payment_method_collection;
@@ -244,15 +258,17 @@ exports.createCheckoutSession = functions
         }
         if (promotion_code) {
           sessionCreateParams.discounts = [{ promotion_code }];
-        } else {
+        } else if (mode !== 'setup') {
           sessionCreateParams.allow_promotion_codes = allow_promotion_codes;
         }
         if (client_reference_id)
           sessionCreateParams.client_reference_id = client_reference_id;
+
         const session = await stripe.checkout.sessions.create(
           sessionCreateParams,
           { idempotencyKey: context.params.id }
         );
+
         await snap.ref.set(
           {
             client,