He bought licences 1 year in 2016 (at the end of the dashboard licence term was 1 year in the licence history), and in 2017 he bought renewal 3 years (at the end of the dashboard licence term was 3 years)
I don't know in 2016 and 2017 if licensing mode was co-term or per-device).
All his licence expiration was Jan-2021.
He bought renewal 3 years in Dec-2020. I don't know why but in the dashboard, in the licence history I can see the licences but are not in renewal but are in "add device" with licences term 4 years.
And at the top of the dashboard expiration is Jan-2023, So 2021 -> 2023 = 2 years.
Sorry for my english I am not an englishman.
I don't know if I can put screeshot ?
thanks