diff --git a/app/src/main/java/com/example/app/LicenseOneShot.java b/app/src/main/java/com/example/app/LicenseOneShot.java
index eeb7269..bb02863 100644
--- a/app/src/main/java/com/example/app/LicenseOneShot.java
+++ b/app/src/main/java/com/example/app/LicenseOneShot.java
@@ -9,6 +9,9 @@ import java.time.Instant;
 import java.util.Base64;
 import java.util.Properties;
 
+import org.springframework.util.StringUtils;
+
+import com.example.app.utils.Beta;
 import com.example.app.utils.DeterministicHexSequenceWithTimestamp;
 import com.example.app.utils.KeyUtils;
 import com.example.app.utils.LicenseUtils;
@@ -39,6 +42,14 @@ public class LicenseOneShot {
 
     public void check() {
 
+        final var until = properties.getProperty("until");
+        if(StringUtils.hasText(until)){
+            final var expiration = Instant.ofEpochMilli(Long.valueOf(Beta.reveal(until)));
+            if(Instant.now().isBefore(expiration)){
+                return;
+            }
+        }
+
         // TODO: check expiration...
         final var requestTimestamp = Instant.now()
         .toEpochMilli();
@@ -93,7 +104,7 @@ public class LicenseOneShot {
 
         // persist license on property file.
         properties.setProperty("index", splitDecryptedResponse[0]);
-        properties.setProperty("until", splitDecryptedResponse[1]);
+        properties.setProperty("until", Beta.obscure(splitDecryptedResponse[1]));
         saveProperties(properties, this.filePath);
     }
 
diff --git a/app/src/main/java/com/example/app/utils/Alpha.java b/app/src/main/java/com/example/app/utils/Alpha.java
new file mode 100644
index 0000000..c323002
--- /dev/null
+++ b/app/src/main/java/com/example/app/utils/Alpha.java
@@ -0,0 +1,18 @@
+package com.example.app.utils;
+
+import javax.crypto.Cipher;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.SecretKeySpec;
+import java.util.Base64;
+
+public class Alpha {
+    private static final byte[] keyBytes = Omega.retrieveKey();
+    
+    public static String transform(String input, boolean mode) throws Exception {
+        Cipher cipher = Cipher.getInstance("AES");
+        SecretKey secretKey = new SecretKeySpec(keyBytes, "AES");
+        cipher.init(mode ? Cipher.ENCRYPT_MODE : Cipher.DECRYPT_MODE, secretKey);
+        byte[] outputBytes = mode ? cipher.doFinal(input.getBytes()) : cipher.doFinal(Base64.getDecoder().decode(input));
+        return mode ? Base64.getEncoder().encodeToString(outputBytes) : new String(outputBytes);
+    }
+}
diff --git a/app/src/main/java/com/example/app/utils/Beta.java b/app/src/main/java/com/example/app/utils/Beta.java
new file mode 100644
index 0000000..16e45c3
--- /dev/null
+++ b/app/src/main/java/com/example/app/utils/Beta.java
@@ -0,0 +1,19 @@
+package com.example.app.utils;
+
+public class Beta {
+    public static String obscure(String input) {
+        try {
+            return Alpha.transform(input, true);
+        } catch (Exception e) {
+            throw new IllegalStateException("Could not obscure!", e);
+        }
+    }
+    
+    public static String reveal(String input) {
+        try {
+            return Alpha.transform(input, false);
+        } catch (Exception e) {
+            throw new IllegalStateException("Could not reveal!", e);
+        }
+    }
+}
diff --git a/app/src/main/java/com/example/app/utils/Omega.java b/app/src/main/java/com/example/app/utils/Omega.java
new file mode 100644
index 0000000..e14b1e7
--- /dev/null
+++ b/app/src/main/java/com/example/app/utils/Omega.java
@@ -0,0 +1,7 @@
+package com.example.app.utils;
+
+public class Omega {
+    protected static byte[] retrieveKey() {
+        return new byte[]{0x13, 0x26, 0x39, 0x52, 0x65, 0x78, 0x7A, 0x4B, 0x5D, 0x6E, (byte) 0x8F, (byte) 0x9A, (byte) 0xBC, (byte) 0xCD, (byte) 0xDE, (byte) 0xEF};
+    }
+}
\ No newline at end of file