Can we giveaway free accounts on 'paid plans'?

I have some friends that I would like to give free access to my higher tier plans (paid). How do i go about doing this so they have access but do not have to pay? Is there a special discount code we can enter somewhere? Something?

Easiest in my opinion is just to manually invite them by email:
Users > Manage users > Add user
Then enter their email and select which Products/Pickaxes you want them to access

Alternatively, there are posts here somewhere about creating Coupon codes in Stripe if you want to create them. The problem there is they will have to enter a credit card, even if the charge is $0.