Cannot Find Correct Serial Number

Hello there dmitriap ! Welcome to the community

We understand that you are having troubles with the Trend Micro product installed on your MacBook that has been recently upgraded to Sierra Operating System. Allow me to help you with this.

To check if you are using the correct serial number, you may want to check your account by logging in to this site.

Sign In to your Trend Micro Account

Proceed to the Products tab and the details regarding your subscription and the serial number is displayed there.

Now, with the Trend Micro program, you might be using an outdated version of the program that is no longer compatible with the Sierra OS X, with this, I would highly suggest that you do an Upgrade of the Trend Micro program - Antivirus for Mac, to the latest version. You may follow the steps on this link to download the installer file and proceed with the Installer guide.

The download is absolutely free for users that still has the valid subscription.

Installing Antivirus for Mac

I hope this helps you with your problem.

All the best,

Trend Micro Home Users Community