Plus subscriptions cannot be transferred between accounts. This article covers this ChatGPT limitation
To transfer your Plus subscription from one ChatGPT account to another, you first need to cancel the subscription on your current account. Then you can sign up for Plus on the new or second account.
See How to cancel a ChatGPT Plus subscription?
How can I migrate chat history from one ChatGPT account to another ChatGPT account?
Follow the steps for transferring conversations from one ChatGPT account to another ChatGPT account, ensure you have only one Plus subscription, and transfer any data to your final ChatGPT account because accounts cannot be merged.