If I upgrade to month to month can I change to annual and still get the grandfathered price?

I am considering 1 to 2 year billing but want to see what the commitment looks like. Also, is referral link no longer available. Count not find it.

No,  any change performed later on will based in the new pricing structure. So if you upgrade on a monthly basis and then want the annual one, the subscription will be based in the new rate.

Also, I am not sure which referral link you are talking about, please give us more details to assist you better.