Is it allowed to use the design in external web hosting?

Yes. You can export the site and import into other hosts.

thank you for the reply,
if I will use a free template does creditng nicepage is a must?
and do i need a premium account to do this?

The free Starter version allows 1 site, up to 5 pages, and does have footer ads.

Thank you,
and if i pay for the PERSONAL license does it allow me to remove the footer ads?

Yes. Any license removes footer ads and unlimited pages.