Steps to use the CCB app to check the validity period of a credit card:

1. Open the CCB app and log in to your account.

2. Find and click the "Credit Card" option on the homepage or navigation bar.

3. On the credit card page, find and click on the relevant credit card account.

4. After entering the credit card account, search or swipe on the page to see more options and select the "Expiration Date" (sometimes labeled "Expiration Date") option.

5. After clicking this option, the system will display the validity period of the queried credit card.