I'm a software developer for business databases. And I would like for my customer to come to my website create an account and purchase Development hours between 5,10,15, & 20 hours at a time. I'd like to be able to update each user's remaining time they have on their account. Meaning this, if a user is wanting 2 hours worth of work completed, then they would need to purchase a minimum of 5 hours but what I would do is go into that user's account and change their 5 hours remaining to 3 hours remaining. This would allow the user to log in and check how many hours they have left for future development needs.
Any Idea how I can accomplish this?