The Windows 7 license does not permit you to use it as a production SQL Server. It is licensed for a single user, with an exception that allows up to 20 other devices to connect to it, but only for "File Services, Print Services, Internet Information Services and Internet Connection Sharing and Telephony Services".
Vagy
Only the single primary user of the licensed device may remotely access his/her Windows desktop OS without the need for an additional license. In the scenario you provided - I read that you are treating Windows 7 Pro as a server. If so, then each accessing device would require either active SA or Windows VDA.
Persze feltételeztem, hogy nem egy user használja távolról. ;)