Hello,
In your case, you will have to first purchase the permanent license for The Grand SE3 trial which costs: €99.99
And then you will have to purchase the upgrade from The Grand SE 3 which costs: €49.99
€99.99 + €49.99 = 149.98
In the end it is the same thing.
If you want The Grand 3 you should simply go directly for the full version. You will save €0.98 
Best regards,
GN