The Register reports
that GitLab is planning to start deleting repositories belonging to free
accounts if they have been inactive for at least a year.

GitLab is aware of the potential for angry opposition to the plan,
and will therefore give users weeks or months of warning before
deleting their work. A single comment, commit, or new issue posted
to a project during a 12-month period will be sufficient to keep
the project alive.

Source: LWN.net – GitLab plans to delete dormant projects in free accounts (Register)