The on-sale date is from the publication date recorded in the Catalog of Copyright Entries, Part 2, Periodicals, 1944, New Series, Vol. 39, No. 1.
This appears to be the issue that drops the "Inc.", although the available indicia scan does not include the far right edge where we would be able to verify. However, the typographical alignment compared to nearby issues makes it pretty certain that there is no "Inc." as the starting points of later lines would show up differently if it were present.