Since you are planning to sync Windows sticky notes between your PCs and devices, then you need the Subscription plan. The pricing is yearly basis. The license allows you to install Notezilla on any number of Windows computers as long as they are all synced with the same sync account and used by same user. You can sync your notes using Notezilla apps for iPhone/iPad & Android also. They sync automatically with each other.
More details are here: https://www.conceptworld.com/Notezilla/BuyNow
You can purchase from the same link.
Also, please note that we don't have a Mac version. However you can access your notes from Safari on Mac using https://www.notezilla.net
Do check out this short video on the sync feature;