Alasdair Taylor's Answer

If I understand this question correctly, you are asking whether you should use a free downloadable website template (such as a CSS file plus HTML skeleton, or a theme for a CMS) for a commercial website. 

If the licence under which the template is made available permits commercial usage, then you can.  If not, you can’t.  If there is no express licence, then the sensible approach would be to ask the template creator whether they object to the commercial use of the template.