Escrow locks your files. I am not 100% sure how it works with designing since I’ve only locked lua files. But basically Escrow will lock the file(s) to your keymaster, meaning you can’t use this resource without using a license key connected to the resource.
Escrow also blocks any editing of the file so that you can securely sell your resources without having to worry about leaks.
So regarding your question, purchasing it without Escrow protection means you can use it anywhere as well as edit the files, unless he has locked the files in another way.
Detailed post: Introducing Asset Escrow for your resources