change to the licensing
That's correct. You can't back-date a EULA. Solutions prior to that date were licensed for use on as many sites as you want. (Although as WebAssist no has any remaining copies of that last EULA on file, we'll have to make a note of it in our diaries!) 
Sorry to have been so pedantic but I was seeking absolute clarity. All good news for me, so many thanks for the rapid response - much appreciated.


