Thank you so much for your continuous and tireless help on any question!
I made it work, thanks to you.
Here is the code, it may be helpful to someone, some time
<qdbapi>
<udata>mydata</udata>
<usertoken>%user.token.b3p533_s9a_xphg.Aleksandar Johnson%</usertoken>
<apptoken>dzhv6g3d9cdbzkma2jfdjqb57b</apptoken>
<field fid="31">[old.Planned Exit Date (Ideation)]</field>
<field fid="13">[Record ID#]</field>
<field fid="8">[Product Name]</field>
<field fid="9">[Product Family]</field>
<field fid="10">[Product Release Version]</field>
<field fid="6">[Planned Exit Date (Ideation)]</field>
<field fid="20">%curdate%</field>
<field fid="19">[Last Modified By]</field>
</qdbapi>