The activation key for Mobile Security purchased from Google Play or Amazon App Store is only good for one Android phone or tablet. You can transfer it to another Android device but this will deactivate Mobile Security from the first activated Android device.

To transfer your Mobile Security license to another phone or tablet, refer to this Knowledge Base article: How to transfer protection from one phone or tablet to another.

You can use the serial number of Maximum Security to activate your Mobile Security program. Take note that since both programs (Maximum Security and Mobile Security) are using the same serial number, both programs will expire on the same date. 

If you are using either Internet Security or Antivirus+, you are entitled for a 7-day free trial of Mobile Security. There is no need to enter the serial number to activate Mobile Security, all you need to do is to sign in using your Trend Micro Account.

If you are still getting the "Invalid Activation Key" error message, make sure that you are signed in using your Trend Micro Account or the email address you used to purchase and register Mobile Security.

To check if you are signed into Mobile Security using your Trend Micro Account, follow the steps below:

1. Open your Mobile Security App.
2. Tap the Menu key.
3. Tap Settings.
4. Under Account and Subscription, check the registered email address.
   If the registered email address is not the same as your Trend Micro Account, follow the steps below:
   1. Open the Mobile Security app.
   2. Tap the Menu key.
   3. Tap Settings.
   4. Tap Sign out.
   5. Enter your password, then tap Sign out.
      

      If you forgot your password, tap Forgot your password? to retrieve your password.

   6. Go to the Menu again.
   7. Tap Settings.
   8. Tap Setup an Account.
   9. Enter the email address and password of your Trend Micro Account.
   10. Tap Sign in.
       

       If you encounter issues while activating the app, contact our Technical Support for assistance.