Some of our archived files are assigned to LOs and LPs who have left the organization. Will our user license cause us any difficulty accessing those files ?

No. The user license applies to active BytePro users (those users who will log into the data folder). LOs and LPs may be imported as assignees with those archived files. You may sort and view those files by the original LOs and LPs, or reassign them as it becomes convenient on a file-by-file basis.