the customer should be able to call the installing company and get the password if the company is willing to work with them, if not sounds like you will be starting from scratch, you might have to explain to the client that a situation might come up like that.

I have run into several jobs like that with Crestron....previous company out of business and no files left on site...had to start from scratch...and system was controalling several rooms of AV, lights, shades, gates, pool, security, had lock outs on the phone system, we tried contacting to original company and the owner sent us the laptop that was used for programming but all we could extract was the lighting program and some beginings of the crestron. So we ended up replacing alot of equipment and all of the crestron anyway so we really had to start from scratch to make it right.

and adding a password to protect the work doesnt mean everyone will use it on all jobs. I will probably not use it on my jobs as we are the only RTI dealer for 100 miles or so