Just one. ( As it states in the Terms of Service )
1. Server Usage
Personal accounts are to be used by the primary owner only. Personal account holders are not permitted to resell, store or give away web-hosting services of their website to other parties. Web hosting services are defined as allowing a separate, third party to host content on the owner's web site. Exceptions to this include ad banners, classified ads, and personal ads. x10Hosting reserves the right to refuse service and /or access to its servers to anyone. Each individual is allowed ONE account only.