If you are using your own domain name, then it is ok to move around free or paid host, if you are planning to build your website with subdomains offered by free web host, then you will need to rebuild your traffic again (i.e search engine traffic, educate existing website visitors of the new site etc.) when you decide to go with paid hosting in future, this is because you will not be able to take the subdomain with you when you move to paid host
That is why I always advise people to register their own domain name whenever they want to start a website.
