Word meaning not knowing when to stop

Is there a word that means "not knowing when to stop"? I haven't been able to think of one as of yet.

It does rather depend on context. Reckless will often fit, but so might unrestrained, undisciplined, careless, and several others.

Personally I think the best "single-word" answer is intemperate - having or showing a lack of self-control; immoderate. It's particularly associated with not knowing when to stop drinking alcohol, but that doesn't prevent its use in other contexts.

Note that temper has many meanings; in "intemperate" it's the verb to moderate, or tone down.

Depending on context, you may use unrestrained or unbridled.

Incessant. continuing without interruption; ceaseless; unending

Compulsive might do what you want.