If you have been using Moneydance since 2016 it is likely that you are using Moneydance 2015. since then Moneydance 2017 & Moneydance 2019 have been released.
If you purchased Moneydance directly via the Moneydance website you are entitled to the version you have purchased, the next major release and every update for the two versions. Hence if you purchased 2015 you would also be entitled to Moneydance 2017.
Further to this you would be able to purchase further upgrades at a 50% discount.
If you purchased Moneydance from a third party, like for example the Mac App store none of the above apply.
The latest version of Moneydance 2015 can be downloaded from: