Most of the models I have bought carry a standard license. The key phrase is "or in other Games". In this case my understanding is that you are not limited to any specific software you can include these models in. You should always check. I can't say this applies to all. Most just ask for a notice usually in the credits:
Some or all of the game assets used in this game are (c) Sellers name.
All Rights Reserved.
Grant of Licence
In consideration of the Customer's promises herein (including without limitation the Customer's obligations in clause 7 of this Licence Agreement) the Seller hereby grants the Customer a personal, non exclusive, perpetual, non transferable, royalty free licence to:
modify Assets and integrate Assets in "Commercial Games" (as defined below) created using FPS Creator, FPS Creator X10, Dark Basic Professional, Dark GDK or in other Games; and
issue copies of such Commercial Games (and permit others to issue copies of such Games) to the public for commercial purposes.
A "Commercial Game" is a Game which is either: (i) commercially exploited by any person (including, by way of example only, a Game which is distributed in return for payment or any other benefit); or (ii) reproduced in more than 100 copies.
A "Game" is an entertainment software game whose sole purpose is to entertain its user without further modification. The term Game expressly excludes: (a) any software tool or software product which can (or might) be used in order to create further games or other software products; and (b) any software library, compilation or collection of graphics and / or sounds and / or other assets or works from which a particular graphic or sound or other asset or work may be extracted to be used independently of the software in which it was first incorporated; in each case irrespective of whether or not the primary purpose of such software is to entertain its user.
Some or all of the game assets used in this game are (c) Sellers name.
All Rights Reserved.
Grant of Licence
In consideration of the Customer's promises herein (including without limitation the Customer's obligations in clause 7 of this Licence Agreement) the Seller hereby grants the Customer a personal, non exclusive, perpetual, non transferable, royalty free licence to:
modify Assets and integrate Assets in "Commercial Games" (as defined below) created using FPS Creator, FPS Creator X10, Dark Basic Professional, Dark GDK or in other Games; and
issue copies of such Commercial Games (and permit others to issue copies of such Games) to the public for commercial purposes.
A "Commercial Game" is a Game which is either: (i) commercially exploited by any person (including, by way of example only, a Game which is distributed in return for payment or any other benefit); or (ii) reproduced in more than 100 copies.
A "Game" is an entertainment software game whose sole purpose is to entertain its user without further modification. The term Game expressly excludes: (a) any software tool or software product which can (or might) be used in order to create further games or other software products; and (b) any software library, compilation or collection of graphics and / or sounds and / or other assets or works from which a particular graphic or sound or other asset or work may be extracted to be used independently of the software in which it was first incorporated; in each case irrespective of whether or not the primary purpose of such software is to entertain its user.