What is the difference between perpetual licenses and subscriptions?

We are not switching from software as a product to the SaaS model. We will continue providing our products as on-premises software, but on a time-limited license basis. With our subscriptions, the right to use the software is leased with payments on a periodic basis.

If purchasing monthly (only for direct purchases):

Usage rights to all releases are granted by JetBrains for the monthly subscription term. If a customer pays for 12 consecutive months, they receive a perpetual fallback license for the exact version available when the 12 consecutive months term started.

If purchasing annually:

Usage rights to all releases are granted by JetBrains for the yearly subscription term. In addition, the customer is immediately granted a perpetual fallback license for the exact version available at the time of the yearly subscription purchase. This fallback license will allow the customer to use that exact version of the software should they decide not to continue with subscription payments.