My attorney has worked on a case for the last seven years. How much can he charge for his services?

What kind of case and why so long ?

He can charge however much it costs based on his hourly rate and any additional fees and costs incurred. Unless they agreed to a flat fee up front in writing (something I doubt they would do in anything but the most simple and quick cases except contingency which is a contracted percentage plus additional costs) otherwise there is no upper limit.

Most attorneys I know charge per hour. However, depending on the type of case, it may be on a contingency. That means they either get paid nothing if they loose, or a percentage of the winnings should you win the suit.

It really depends on what you are suing for.

Was there a written contract and, if so, what did the contract provide?