Azure Log Analytics Workspace should have a retention period set to ensure logs are retained accordance with industry standards as well as common compliance and regulatory guidance. The most common timeframe cited with regards to retention periods is 90 days or more.
In Azure Console -
In Terraform -
References:
https://learn.microsoft.com/en-us/azure/azure-monitor/
https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/log_analytics_workspace#retention_in_days