Digital Rights Management Solution for Online Contracts

We are an industry group that represents our members in the Building and Construction industry. Currently we offer members a ‘Home Building Contract” in hardcopy form, however we would like this to be able to be a digital contract that can be licensed / rights managed to stop duplication of contracts, and thus payment. It is currently an indesign document, and has been converted to an online document for testing purposes. Where it can be filled in and printed on the computer. It does not however have the ability to disable printing after a certain amount of prints, or does not have a numbering system for individual contracts. We require somebody to create a contract system that allows us to rights manage them without it being difficult for the buyer to purchase. Not sure if a credit card purchase system would work? The contracts would have to be in a system that attaches a Contract Number to each purchased contract, and delivers the contract to either an email address, or a direct download. Perhaps the best solution would be a website which housed the contract. Someone would select how many contracts they needed, input credit card details, then the contract would either be emailed, or downloaded through a download manager and delivered to the purchaser with each contract now containing a unique contract no. The contract number will need to appear on the cover, and every page inside as a watermark.