For a fee, the fee is 2 yuan per month. The specific activation method is:

1. Open the Bank of China app and log in to your account.

2. Find the account management option on the homepage and click to enter.

3. Click More Options in the upper right corner of the account management interface.

4. Select the account change notification option in the more interface.

5. Click to activate SMS notification.

6. You can see that the charging standard is 2.00/month, click Next.

7. Then click "Confirm" below to complete the activation.