Hi Tuan,
I just wanted to thank you for making the documentation for your extensions available without being logged in as a subscriber. A lot of Joomla extensions don't allow this because they consider it part of the paid support, but it is very helpful for our clients (as the end users) to have instructions on how to use the extensions. We as the site developers are usually paying for the licenses, but our customers are the ones using the website as admins, so it's necessary to give them access to documentation!
Your paid support that you provide is amazing and we are happy to keep up the license fees for updates and all of your help!
Karen