The constant _RENOUVELLE_ALEA defines the duration of the randomness for cookies in seconds. In particular, it allows you to modify the duration of sessions. The default value is 12 hours.
Be aware that for some cookies, a multiple of this value is used (for example _RENOUVELLE_ALEA * 4)
You can change this duration by customizing the value of the constant in your file config/mes_options.php (see the article dedicated to it).
You may want to set a very long duration to avoid users having to reconnect too often.
Example :
// 3 months duration
define('_RENOUVELLE_ALEA', 3600*30*3);
Example :
// reduce the session value to one hour
define('_RENOUVELLE_ALEA', 3600);
Warning: This constant is a low level constant that can only be defined in the file config/mes_options.php. It is not possible to modify it in the code of a plugin or a template.