Yes! If you are paying for a Yearly plan you will be moved up to the next plan for each 4 new users you refer.
If you are paying for a monthly plan, for the first 4 users you refer you will be moved onto a yearly plan and then for each successive 4 new users you will promoted onto the next yearly plan.
Currently on the Lite Monthly plan,
Refer 4 users, you are now promoted to the Lite Yearly plan,
Refer 4 more users, you are now promoted to the Basic Yearly plan.