Registered capital is not the same as working capital.
Registered capital is what you registered with the Department of Business Development, Ministry of Commerce of Thailand, as the capital of the company, at least 25% of which has to be paid up. When part or all of your registered capital is paid up, you have some money in the company to spend for your business operation. This money can be all or part of your working capital.
On the other hand, working capital is the money you have to run the business operation which you can get from the paid up capital of the company and or borrow from other people (banks, directors, etc). Thus, you can use all of your funds from the paid up capital in the business or even lend it to another person.