Romain Dheilly

As long as agent is installed and communicates with the ESET PROTECT server, you can apply an Endpoint policy which will disable password protection. You don't have to know the password when disabling it via policy.

EEA = ESET Endpoint Antivirus
EES = ESET Endpoint Security
As Michal wrote, if you send a software install task and do not select a license, the existing license will be kept. This is recommend unless you must change the license key, e.g. after you have upgraded to a higher-range ESET product (ie. from EEA to EES). If you select a license key (even if it's same), deactivation will be performed first.

Hello @Romain Dheilly, even if you have just used the software install task, the application should work in a way, that it will keep the license (even if no license was selected in the software install task). I will check with the teams here, whether they have witnessed similar behavior from the other customers.
One of the things that I know tends to happen is, when customer accidentally installs EES and his license is for EEA, that will result in products being not activated, as the license and product do not match. When you have attempted the manual reactivation (vie the software install task), what was written in the task details / executions history? What was the reason for it to fail?