When you purchase a permanent license, you are able to run any versions of the application that are released before the end date of your maintenance contract - this is the “maintenance date”. In practice, the maintenance date is the version limit of the license.
Permanent licenses do not expire, you will always be able to run versions of the application that were released before the maintenance date of the license. If you do not renew your maintenance then you won’t be able to run versions released after the maintenance date.
Your first purchase of a permanent license comes with a maintenance plan, typically of 1 year.
As an example, when purchasing a permanent license on 1st July 2019 we would issue a permanent license with a maintenance date of 1st July 2020. The license will show this maintenance date as 2020.0701. With this license you can forever run any versions of the application that were released before 1st July 2020.