Thanks for your responses.
With Quite often I meant multiple times in the last half to three quarter year. (3 times)
Because I’ve just been busy with installing my new PC (switch from Mac) and try all kind of music styles, I didn’t use BFD a lot the last year.
Therefore this error message occurred almost once every two times I started BFD.
I didn’t realise the possible presence of a 3 month license check.
So I thought it just happens very often. (the more you use it the more it occurs)
But I think it could be just that 90 days check and not as I thought a reoccurring bug.
It is a bit inconvenient for an offline computer, but if it is just 4 times a year, and not occurring randomly than it is not a real big deal.
The coming weeks I will definitely use it more often on some projects, So I can check whether it stays active for the next 90 days.
To be honest I don’t like it that developers don’t make it easier to keep software running on an offline computer. But unfortunately that is how it is nowadays. (I even had to skip some software that required constant internet connection)