License code rejected

Last night I worked on a website using Rapidweaver 7.4.1 on a MacBook Pro with Sierra. Everything was OK. This morning when I tried to open Rapidweaver I was asked to activate the license, but the license code I have been using since I first got RW 7 is being rejected for reasons unknown. The only “new” thing I did last night was to upgrade Stacks to 3.5.3. Advice will be very much appreciated. Thank you.