If you purchased a Premium subscription and sent your Blinks to Kindle then yes: the Blinks you sent to your Kindle will remain there, even if you cancel your Blinkist subscription.
Will the Blinks I sent to Kindle remain after my subscription ends?
If you purchased a Premium subscription and sent your Blinks to Kindle then yes: the Blinks you sent to your Kindle will remain there, even if you cancel your Blinkist subscription.