Enlighten me - are you pre-paying for some sort of legal services (wills, family law, crim?) in the future at a discount rate? Is that the hook? Presumably, they've paid some affiliated lawyer/law firm in advance for some basic services?
They are betting that, as with many gift certificates, you will never cash in. The services offered are probably very basic, and anything at all useful will require payment over-and-above the basic cost. Presumably, these services are also not being offered by big, reputable firms, so by the time you need them, the lawyer in question could be out of business/disbarred.