The data is stored locally by default. If you create a sync account then it is stored locally as well as on the server. To create a sync account right click on  
Notezilla  icon (next to the clock)  in the taskbar  and select Sync from the menu.
In the new version we have a added "Offline" memoboards support. If you create notes inside offline memoboards then they are never sent to the server and only remain on your computer. 
Of you choose to cancel the subscription later, syncing will stop. But you can continue to use the product locally.
 
Notezilla  also keeps 5 backup copies of  
Notezilla  data locally on your PC which you can restore using the  
Notezilla  Troubleshooter app.