This is an update (latest response is shown below). I've been notified by Malwarebytes support that I was sold and "old" license. The packaging was not dated, did not indicate that the software has a shelf life, and did not indicate Windows only machines. It operated from January of this year thru last week on my Mac's (and the Windows machine).
I purchased a valid license. Malwarebytes should step up and resolve the problem, not ask for additional money.
No admin on this site have chosen to chimed in on this.
It's interesting to note the hairsplitting going on here, purchased from the website versus a retailer.