rickhumphries joined the session Proof of Purchase? How can technology assist in the elusive burden of proof needed forcontract cheat 2 years, 8 months ago Proof of Purchase? How can technology assist in the elusive burden of proof needed forcontract cheat Visit group Share this:Click to share on Twitter (Opens in new window)Click to share on LinkedIn (Opens in new window)Click to share on Facebook (Opens in new window)