Is there a free version of network billing software like Deep Blue and Const?

Const, a billing system, is a good product and very professional. I contacted this company and they offered a remote trial. I also tried other companies' software. In contrast, this software is excellent in function and operation design. This kind of products are system-level products and cannot be free. If it is free, it is also a small software. There are many general problems, and the quality of functions is also problematic. Who dares to use it? Dude, here's the bill. It's a money-making software. If there is something wrong with the billing, which affects the income and profit, netizens will have to find you trouble, and you will lose a lot.