Cant get it installed

Had the free version. Decided to upgrade. Paid my $4.99 and downloaded to my IPad Pro. It doesnt recognize I have paid and defaults to a message telling me to upgrade! And I first deleted the old app and restarted my IPad. Frustrating as I think its a good app if I can get it installed.

KLM MX about Planner Pro - Daily Planner, v3.3.0