diff --git a/README.md b/README.md
index 63c3e8d..b7f1c5d 100644
--- a/README.md
+++ b/README.md
@@ -8,13 +8,15 @@ An Package to interact with an mock stock exchange
 | ----- | ------ |
 | Key   | 8 Bytes |
 | Operation | Byte |
-| Asset | Byte |
+| Asset | 2 Bytes |
 | Price | Float64 |
 | Volume | Float64 |
+| Expire (Unix) | uint64 |
 | CRC | 2 Bytes |
 
 ## TODOS
 - [ ] Test it  
 - [ ] Make it configureable  
-- [ ] Implement expire date  
+- [x] Implement expire date  
+- [ ] Change Key to uuid
 - [ ] Document it  
\ No newline at end of file
diff --git a/spf.go b/spf.go
index f9a78f8..4f05e39 100644
--- a/spf.go
+++ b/spf.go
@@ -12,20 +12,21 @@ import (
 type SimpleFinancePackage struct {
 	Key       [8]byte // 8 bytes for the key
 	Operation byte    // 1 byte for operation
-	Asset     byte    // 1 byte for asset
+	Asset     uint16  // 2 bytes for asset
 	Price     float64 // 8 bytes for price (float64 for precision)
 	Volume    float64 // 8 bytes for volume
+	Expire    uint64  // 8 bytes for expiration date
 	CRC       uint16  // 2 bytes for CRC
 }
 
 func ParseSimpleFinanacePackage(data []byte) (*SimpleFinancePackage, error) {
-	if len(data) != 28 {
-		return nil, errors.New("invalid packet size, expected 28 bytes")
+	if len(data) != 37 {
+		return nil, errors.New("invalid packet size, expected 37 bytes")
 	}
 
 	//Check CRC
-	check := binary.BigEndian.Uint16(data[26:])
-	if check != crc.Calculate(data[:26]) {
+	check := binary.BigEndian.Uint16(data[35:])
+	if check != crc.Calculate(data[:35]) {
 		return nil, errors.New("CRC check failed")
 	}
 
@@ -41,9 +42,12 @@ func ParseSimpleFinanacePackage(data []byte) (*SimpleFinancePackage, error) {
 	if packet.Price < 0 || packet.Volume < 0 {
 		return nil, errors.New("price and volume must be non-negative")
 	}
-	if packet.Operation > 127 { // Example: Valid operation values are 0-127
+	if packet.Operation > 127 { // Valid operation values are 0-127
 		return nil, errors.New("invalid operation value")
 	}
+	if packet.Expire < 946684800 { // Expire date must be after 2000-01-01
+		return nil, errors.New("invalid expiration date")
+	}
 
 	return &packet, nil
 }
@@ -67,6 +71,9 @@ func EncodeSimpleFinanacePackage(packet SimpleFinancePackage) ([]byte, error) {
 	if err := binary.Write(buf, binary.BigEndian, packet.Volume); err != nil {
 		return nil, fmt.Errorf("failed to encode volume: %w", err)
 	}
+	if err := binary.Write(buf, binary.BigEndian, packet.Expire); err != nil {
+		return nil, fmt.Errorf("failed to encode expiration date: %w", err)
+	}
 
 	// Calculate and write CRC
 	packet.CRC = crc.Calculate(buf.Bytes())
diff --git a/spf_test.go b/spf_test.go
index 1ee4512..5d06c6e 100644
--- a/spf_test.go
+++ b/spf_test.go
@@ -15,6 +15,7 @@ func TestEncodeDecodeCustomPacket(t *testing.T) {
 		Asset:     2,
 		Price:     1234.56,
 		Volume:    7890.12,
+		Expire:    946684801,
 	}
 
 	// Encode the packet
@@ -24,8 +25,8 @@ func TestEncodeDecodeCustomPacket(t *testing.T) {
 	}
 
 	// Check the encoded length
-	if len(encoded) != 28 {
-		t.Fatalf("Encoded data has incorrect length: got %d, want 28", len(encoded))
+	if len(encoded) != 37 {
+		t.Fatalf("Encoded data has incorrect length: got %d, want 37", len(encoded))
 	}
 
 	// Decode the packet
@@ -76,6 +77,7 @@ func TestInvalidPacketValues(t *testing.T) {
 		Asset:     2,
 		Price:     1234.56,
 		Volume:    7890.12,
+		Expire:    946684801,
 	}
 	encoded, _ := EncodeSimpleFinanacePackage(validPacket)