Look up one directory from Files, so go up to FPS Creator, and you will see a folder called licenses. (Imagine that)

Look in there for the various model licenses from items purchsed through the TGC store.
I'm pretty sure the model packs are licensed the same as the stock media included with FPSC.
X10 commercial license is $1,000 for relasing games (1 time fee for unlimited # of releases), but you don't have to pay it until you have grossed $5,000 from your game(s).
I think the media can be used in any game release, so the licenses for the engine used would be the difference here between X10 and X9.
However, if I grossed $5,000 or more from a game that I used X10 assets in, then I would pay TGC the $1,000 for the X10 license whether I used another engine or not.
That is only a one time fee that is only due after you have earned more than enough to pay it. (then you could use the assets anytime for any project without worries)