Connect to API from an unattended process

We are working on a background process to sync contact data into infusionSoft. The process runs unattended and does not have a UI. Is there a way to connect to the API that does not require the user to “log in.” We noticed the fact that we can create an access and refresh token through the Admin page, but the refresh token expires in 90 days. Is there a programmatic way to keep the authentication alive / secure without having to manually generate tokens every 90 days?