Adjective : gainful employment.    From Dictionary.com. 

In the enquiry into the advantages relatively of foreign and colonial export trade, it is not pretended literally to build upon the premises here established; the analogy would not always be strictly in point, but the fact resulting of the greater gainfulness of one description of trade over another is incontestable, and in the national sense perhaps much more than the individual.    From Wordnik.com.  [Blackwood's Edinburgh Magazine — Volume 54, No. 337, November, 1843] Reference

Under modern conditions of large business, particularly, the relation of the discretionary businessman to industry is that of authoritative permission and of authoritative limitation or stoppage, and on his shrewd use of this authority depends the gainfulness of his enterprise.    From Wordnik.com.  [An Inquiry Into The Nature Of Peace And The Terms Of Its Perpetuation] Reference

The case in question is one of the most meritorious known to the records of modern business, and while it will conveniently serve to illustrate many an other, and perhaps more consequential truth come to realisation in the march of Triumphant Democracy, it will also serve to show the gainfulness of an unreservedly canny consumption of man-power with an eye single to one's own net gain in terms of money.    From Wordnik.com.  [An Inquiry Into The Nature Of Peace And The Terms Of Its Perpetuation] Reference

A liberal education for its own sake, and for its usefulness to others, rather than its gainfulness to themselves; and a new need of the help that they can give has grown up with their new power to give it.    From Wordnik.com.  [The Congress of Women: Held in the Woman's Building, World's Columbian Exposition, Chicago, U. S. A., 1893, With Portraits, Biographies and Addresses] Reference