During the setup of a line of credit, you can choose if you want it to be a recurring budget or a one-time budget. If you choose a one-time budget, then the people you give access to use that line of credit will lose access at the end of the expiration automatically.
If you choose a recurring budget, then the line of credit will be available to use until you deactivate it. You can deactivate it at any time using the management portal by clicking on the Lines of credit tab.