NOTE: this currently applies to JumpStart Embedded Tools for Cortex only, and not to JumpStart C for AVR
Purchasing a JumpStart Embedded Tools (V9) for Cortex license gives you a perpetual right to use the compiler software as released at the time of purchase, as long as the terms of agreement are followed. You may request technical support, and you may upgrade the software to a later V9 release if your maintenance agreement is current. A license purchase includes 12 months of maintenance agreement. You may purchase additional terms of maintenance whenever you choose.
For example, let's say you purchase a license on March 5th, 2018. This means that your license is valid for any V9 versions released up to April 30, 2019 (we round up to the following month).
To run versions released after April 30, 2019, you need to purchase a 12-month maintenance agreement. You may purchase maintenance at any times.
To reiterate: an expired maintenance agreement does not disallow you to run any versions that you were able to run prior to the expiration date, it only disallows running versions that are released after expiration.