Version 11 was released October 2018. Not sure about v11.5 (earliest reference I can find is Oct. 2019), but according to HERE Maps they update every 12-18 months.
Have there been many new roads added in your area, or do you travel a lot (I mean really a lot)? If not, updating isn't very critical, especially for the price (I'd wait for the $99 sale they run every so often). Many users see the maps as pointless since the navigation system is pretty much trash, and you might be better off using your phone.