That may well be the case, I am still not sure if I unlocked Mercalli on both laptop and desktop, prior to re-installing v14 a second time. Problem appeared after reinstalling v14. So could be Mercalli saw it as 3rd go. I sent similar query to Mercalli, they also have a phone number, if i’m desperate!
I had a look on Prodad site, like you, I just don’t know what their policy on number of installs/activations is. Its a great program/plugin for sure. Thanks.