【Paying】 ,  【gainful】 ,  【remunerative】 ,  【lucrative】 ,  【profitable】  share the meaning of bringing in a return in money.

【Paying】 often implies only such a return, but it may imply a satisfactory return for the labor or effort or expenditure involved (as in a venture, a business, or a trade).

【Gainful】 applies chiefly to an endeavor (as a business or a trade) that leads to a money return whether large or small, but it may apply to persons or their acts that are motivated by a desire for gain.

【Remunerative】 suggests a rewarding of labor, effort, or expenditure and often implies a profit or recompense that exceeds what is usual or customary.

【Lucrative】 carries a stronger implication of large returns and applies to a business, trade, or profession or to an enterprise or undertaking that succeeds beyond one's hopes.

【Profitable】  also is applied to what is rewarding, but it need not imply a money return (see BENEFICIAL ); however it usually suggests such returns, not necessarily in a 【lucrative】 manner but in any degree that is consonant with one's wishes or hopes.