I am working on a project for a property management company. There is the back end system that stores all of the tenants and property portfolios, and a front end website that a
open up the MY PROJECT file in Solution Explorer, and then select the SERVICES tab. Check the "Enable client application services" option and basically fill in the blanks.
Alternatives, is to create a webservice which will do the processing into the membership provider for you or to have your windows service manipulate the membership data structures (assuming they're in a database or similar option) manually.