If you are using expiry dates in a learning plan which contains a SCORM course, when the learning plan expires for the user, the completion status of all content items in the learning plan is reset. If users access a SCORM course that has bookmarking enabled, and the completion event is triggered when the user reaches the final slide, they are automatically marked as complete.
To solve this, you can:
Remove bookmarking, which forces users to consume all content from the start of the SCORM course.
If you don't wish to remove bookmarking, you must change the completion event so that it is not associated with viewing the last slide.