From April 25th 2022, we will be renaming "site plans" to "project plans". In addition, you will be able to publish a project to multiple publishing destinations with a single project plan ($5/month).
Previously, you needed to purchase a site plan for each publishing destination and export option. So, if your project was published on three different destinations, you'd pay $15/month (=$5*3) to remove Vev watermarks.
Nothing — unless you have projects associated with multiple site plans. In this case, your next invoice will be adjusted accordingly. For example, if your project was published to three publishing destinations, your next monthly incurring cost would be $5, instead of $15.
Read more on how to add, remove, and transfer your project plans here.