Do you mean "lease" licenses, or "less" licenses? If "less", less than what? If lease, you can buy them via
http://www.swsoft.com/en/buyonline/plesk75reloaded/ (for Linux). Alternatively, any SWsoft partner will be able to lease them to you for a much lower monthly fee assuming you are buying hosting services from them (it's a violation of the agreement if they lease to you and you aren't using their hosting services).