The SILVA NGS credit system has two types of credit actions:
Executing a project with status "created" does not charge the project owners credit account. Only when an user "executes" the project changing the status to "waiting for approval" he pays for it. The same for cancel projects, if an admin cancels a project the user who payed for it does not get any refund. Only when an user uses the cancel button an refund of the credits is done.