@luisrgtel Dear user, you mentioned that you bought Premium in 2019, however Windy Premium is available from spring 2020. Are you sure you have our App?
Activation process differs based on the platform, where you made the purchase. As described in this article, Windy code "WINDY3822...." needs to be entered only when you bought via desktop (FastSpring).
If you have purchased via App/Google Store, you just need to restore it according to the manual, unless it is already assigned to your account.
Once it is assigned to your account, do you not need to do any other restoration process on desktop separately.
I hope this explanation is more understandable.