I have a component I am building for a client, I am wondering if I can make changes AFTER I download it and not have to re-pay the credits, or do I need to buy it again if I make changes?

If I do have to buy it again, how can I send my client to the sandbox then?

If you make changes, you only pay the few changes you did.

If you remove a functionality that you already paid, it cannot be refunded.

If you don't do any changes, you can download it as many times as you want.