diff --git a/src/lib/contracts/CheckoutResponse.ts b/src/lib/contracts/CheckoutResponse.ts
index 46afa1b..2266064 100644
--- a/src/lib/contracts/CheckoutResponse.ts
+++ b/src/lib/contracts/CheckoutResponse.ts
@@ -14,8 +14,8 @@ export interface Purchase {
     amount_per_cycle?: number;
     initial_amount?: number;
     renewal_amount?: number;
-    renewals_discount?: number;
-    renewals_discount_type?: string;
+    renewals_discount?: number | null;
+    renewals_discount_type?: string | null;
     billing_cycle?: number;
     outstanding_balance?: number;
     failed_payments?: number;
@@ -43,6 +43,13 @@ export interface Purchase {
     updated?: string | null;
     currency?: string;
     license_key?: string;
+    bound_payment_id?: string | null;
+    subscription_id?: string | null;
+    gateway_fee?: number;
+    gross?: number;
+    vat?: number;
+    is_renewal?: boolean;
+    type?: string;
     [key: string]: unknown;
 }