How Server License for Prime Timesheets plugins works
How Server licenses for Prime Timesheets plugin work is that they are perpetual, so even when your license “expire”, you can still continue using the license ; and by “renewing” the license you are only paying for the Maintenance part at 50% of the current purchase price.
When you buy the perpetual license, you have a one year of Maintenance support, and after that one year you can continue with the support with annual fee of 50% of the current purchased price, but it is completely optional.