I don't see any way you can keep it from being copied. You can, however, take steps to make it difficult for other customers to use the copied files.
One simple way is to customize the solution with the company's name and logo when you deliver the copy that they have purchased. You can define user accounts (can be entered automatically in file options) that do not allow editing this company specific data and then use FileMaker Advanced to strip out all full access accounts from this copy.
If "Johns Recycling" gets a copy of "Modesto Junk Company Recycler" from Modesto Junk Company, all screens and hard copy have the wrong company name and logo printed at the top and it will be difficult for them to change it.
Thank you PhilModJunk
That is a good idea.
I know a way but not relevant to filemaker.
Use Kakasoft Shared Folder Protector which is a copy protection tool that is specialized in copy protecting and password protecting shared folders and files on PC, LAN and Network.
Assign shared folder permissions to multi-user groups:
you can come ture permissions control by this program. It's here:http://www.kakasoft.com/password-protect-shared-folder/ , you can have a look.