If my reading is correct, FCC allows the use of RF devices that are unapproved. One condition is that it is used for the purpose of
Evaluation of performance and determination of customer acceptability, during developmental, design, or pre-production states.
ftp://ftp.fcc.gov/pub/Daily_Releases/Daily_Business/2013/db0321/DOC-319712A1.txt
I think the 'determination of customer acceptability' is a loose concept. What does it involve? Couldn't a customer be given a device for use for 3yrs and still be part of the 'customer acceptability' process?