Consulting: web based licensing

We have licensed a single hardware/software solution to a customer for a monthly licence fee. We want to add transparent protection to our system; the software contacts an internet server on installation, then again after every month to obtain a valid licence to continue running. We own and administer our own Linux server. The application is written in Delphi 6, it is a command line utility. We would prefer the process to be completely transparent - no dialogue boxes, etc. The application would exit with an error if a valid license key could not be obtained from the internet server. Either this, or it briefly displays a dialoge box saying "contacting server ... done" every month to continue running. We want absolute minimal interaction from the customers point of view, with automatic relicensing unless we turn it off. This is *not* a coding request - this is a request for someone to do some research, and recommend an existing solution. We have already evaluated the following: [login to view URL] [login to view URL] [login to view URL] [[login to view URL]][1] ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform Modifying a command line application writtten in Delphi 6. The Delphi 6 app contacts a Linux server for its license key, every month.