As of now, we do not have a specific expiry date for the referral link. However, please keep in mind, that after March 31, 2021, Wave users located outside the US and Canada will no longer be able to send Stripe payment-enabled invoices, including auto-payments for recurring invoices. Hence, Stripe payments will be accepted until June 30, 2021 after which the payments will not be processed in Wave (for Wave users outside the US and Canada).
We would recommend you to signup using the referral link before June 30, 2021 to avail the custom wave plan for a year.
Books
Online accounting software
for small businesses.