Louis LamprellYacht charter broker, DMA Yachting
Yes, usually you do.
In Croatia, operating a jet ski normally requires a valid license, and this is not something to ignore or leave until you are already on board. The exact license question can depend on where it was issued and whether it is recognized, so it is important to check this before the charter starts.
We recently put together a full guide on jet ski regulations in Croatia, including accepted foreign licenses and what to watch out for.