Benefit expiry date means the last date to activate your benefits.
You've until your renewal date to redeem the benefits available during your one-year enrollment period. You can find your renewal start date from the Dashboard > Membership > Purchases > Bills & payments page in the Partner Center.
However, you can use product keys for one year from the day you redeem the keys on their respective cloud portals if you renew and have an ongoing Membership enrollment active.
For example, if your benefit expiry date is January 31, 2021, then you need to redeem the keys in the appropriate cloud portal before January 31, 2021. And if you redeem your product key on December 1, 2020, you can use that key until December 1, 2021, even though your benefit expiry date is January 31, considering you'll renew the Membership enrollment after the January 31, 2021 anniversary date.
Should you choose not to renew the Membership enrollment, you'll need to obtain license rights via Commercial Licensing. As indicated in the Microsoft Cloud Partner Program Benefits Usage Guide, Use rights for cloud services subscriptions terminate at the end of Microsoft Action Pack subscription or at the end of a Solutions Partner designation enrollment year or at the end of legacy Gold or Silver benefits purchase. Although Partners may continue to have, access to cloud services past their program enrollment end date, they'll no longer have use rights through the program.
Note
If you have benefits that require a user assignment (such as Visual Studio subscriptions), you can activate and use those benefits for another 30 days after the enrollment renewal date.