Yes. If you cancel your plan, you keep your surveys and all the responses you've collected.
Until your billing period ends, everything works the way it does now.
After that, your surveys and responses stay in your account. You can still open the Results page and export your responses as CSV.
Your surveys stop accepting new responses, and respondents see a "survey closed" message. Renew your subscription to start collecting responses again.
If you don't sign in for 6 months on the free plan, your account and data may be deleted. Export your responses as CSV to keep a copy.
For more details, see What happens to my surveys and data if I cancel or downgrade to the free plan?