Hi Kelvin,
CJT Dev 7.1 has the bug where it will automatically notify you to update to the 7.2 CJT Free version on WordPress.org. However that said, I notice in the backend that you have successfully registered your license key so your CJT Dev 7.1 should update to version 7.2 just fine. It only happens when users do not register their license key. So you should be fine to update to 7.2 via the WordPress plugin updater.
Please also note that you should be able to login and click into your purchase history to download the latest version manually, which is CJT Dev version 7.2. This is found when you hover over your username and then clicking Purchase history. Else you can just click this link: https://css-javascript-toolbox.com/purchase-history/
Kind Regards,
Damian