Can customers auto-update the modules they bought, and what happens if an update fails?

Yes. Products distributed through Digital Revolution can check for and install new releases in one click from the customer's own shop. Before applying an update the module runs pre-flight checks (available disk space, file permissions and required PHP extensions), backs up the current version, then performs an atomic swap. If anything goes wrong during the swap the previous version is automatically restored, so a failed update does not leave the customer's shop broken. Update access is tied to the license: older builds can require active maintenance, so customers keep receiving updates only while their support/maintenance period is valid.