Well, i looked at that site, and i was unable to get much info about these "free models" my french being totally rubbish, (me studying it in GCSEs this year and all) and so i couldnt say for sure, unless of course u CAN read french, (or use a translator) you would have to make sure that you are given express permission by the site or the creator of the content, to use it in a commercial manner, before you go ahead and do.
Most "free" models, are only cleared to be used for private purposes, though there are many sites that offer some free models that can be used in anyway you wish, (often they would have to be credited if used in a commercial form) but generally assume that unless stated otherwise, models belong to the person who created them and so using them commercialy is not allowed, unless of coures if you seek and are granted permision.
hope this helps
EDIT: i see the site is spanish not french, sorry about that, i feel alot better about not understanding ANY of it now tho.
