SCS gets a lot of questions from grad students about rights issues with their dissertations: mostly these are about (1) previous / pending / expected publications of their own, or that they co-authored, or (2) third-party material like figures, illustrations, charts, etc.
Their own publications: Ultimately the publication contract controls. Its terms may limit which “version” of work they can include in the thesis and/or make available online, and when. They usually do not. Look at the publisher policies. In most cases, authors are free to include in their dissertation material that they have submitted for formal publication, but other times the author will need to submit a permission request themselves, and the publisher should indicate how to request permission.
3rd-party materials: For use of third-party, previously published figures, options are: (1) getting permission, in form of a non-exclusive license, or (2) fair use. Use of a single image or figure within a dissertation is typically well-supported by the exception.
Not all figures are protected by copyright in the first place! Data and data representations aren’t protected, so neither are charts/tables/graphs/figures that do nothing more than express underlying facts. However, figures may be protected as original works of authorship where there are creative choices made that do more than represent the underlying data (choices dictated by more than functional considerations).
Copyright exists from the moment your work is fixed in a tangible medium of expression, and persists regardless of whether or not you include copyright notice, or register a claim with the U.S. Copyright Office.
Although registration isn't required for protection, it can provide certain benefits.
Record-keeping function: Registration establishes a public record of the copyright claim, and pins down details about what rights have been claimed.
Prerequisite for litigation: You cannot file a lawsuit for infringement until your certificate and original work are on file with the Copyright Office. Moreover you cannot claim statutory damages or attorney's fees unless your work was registered before the infringement began. So you can't sue until after registration, and you won't receive much in damages for infringements that occur before you've done so.
In most cases, it isn't necessary for you to pay ProQuest to register copyright in your dissertation.
Under U.S. Copyright Law and WUSTL IP Policy (§I(3)(b)), student typically retain ownership of intellectual property rights to works they create. As copyright holder, students may decide whether and when their work will be made available beyond the typical course setting. A lot of this comes down to asking about shared expectations.