I am wondering if I am able to use my Videohive works in another website for showing the customers simple works that have done by me, is not selling my template but using them as showing the customers that I have done this works. Is it ok or it not?
Yes, it´s ok. You won´t sell them in this another site. So they are going to be just samples of your work. You can do that. Also it´s an accepted way to promote your Videohive items
Hi
videohive offers two ways to sell, you have the option to sell to videohive only or you can select to sell to other markets as well, you can show your work on other sites after all is your portfolio, remembering that if you go exclusive author, may not sell to other sites, only samples 
Hope this helps