No, there are no such requirements. The registrant is free to change registrar whenever they want.
Updated 5 Apr, 2020
The Swedish Internet Foundation is an independent, business-driven and public-benefit organization. We work for an internet that contributes positively to people and society. We are responsible for the internet's Swedish top-level domain .se and manages the operation and administration of the top-level domain .nu. The revenue from our business finances a number of initiatives in order to enable people to use the internet in the best way, and to stimulate the sharing of knowledge and innovation with a focus on the internet.