Website with software running on dedicated server

We have an .exe (written in Visual Studio 2012) which will be installed on some dedicated server and run concurrently by different visitors of a new small website that needs to be created. People will subscribe to this website by filling a short Subscription Form and then pay by-the-hour (using their credit cards and/or other funding methods) in order to be able to access and run this program. Therefore there will be a MySQL database for the users, as well as an Admin for me to perform simple tasks (see who registered, pull out their file with their details, etc etc). Security against cheating users, denial of service and other threats is of major importance. Also the system must keep track automatically of how many hours of program execution each user has purchased and how many already spent, in order to allow them access for the remaining time (and possibly issue a warning when their time is about to be consumed). All graphic work for this website is already completed by our design team, so you won't need to worry about website design or website 'architecture'. All texts, images etc for each of the 4-5 pages in total will be given to you (images in Photoshop format, along with their layers). Subscribed users who have already paid for a certain amount of program execution time will be able to access a special page with their chosen username/password and execute the program from there (from WITHIN the website, that is; no downloads or pop-ups of any sort).