Are you asking how long the deal will last for new internet sign ups?  Or are you asking how long the discount will remain on your internet service?

Ah yes, I see how the wording could have gone either way. I’m wondering how long the discount will remain on the internet service, once signed up

They said the promotion would be applied as long as you meet eligibility requirements without any expired date.

hi! Does anybody know what the eligibility requirements are to keep the $20/mo discount? 

It is a simple requirement, you must be a Koodo mobility customer

Just to top up on @Dinh’s response, make sure you are logged into your Koodo Mobility account when you sign up for Koodo Internet, in order to take advantage of the discount.

Some more details about how billing works and setup instructions you can find here 

https://www.koodomobile.com/en/help/koodo-internet-billing-faqs and here https://www.koodomobile.com/en/help/setup-instructions-for-internet-self-installation