The package was designed as an extension of the lastpage
package -- as well as that package's LastPage label (created in
hook enddocument/afterlastpage, formerly \AtEndDocument) it
adds a VeryLastPage (created in the same hook, but formerly
\AfterLastShipout). When more than one page numbering scheme is
in operation (as in a book class document with frontmatter),
the labels above do not give the total number of pages, so the
package also provides labels pagesLTS.<numbering scheme>, where
the numbering scheme is arabic, roman, etc. The package relies
on the undolabl package. Note: The "LTS" of the package name
stands for: "L" = number of Last page, "T" = Total number of
pages, "S" = page numbering Schemes (roman, arabic, ...)

Homepage:
https://ctan.org/pkg/pageslts
