Article 1800

In cases where the buyer has paid the price after the date payment was due, the seller loses the right to terminate the contract unless he does so before he has become aware that performance has been rendered.

In cases where the buyer has paid the price but has breached the contract other than by late payment, the seller loses the right to terminate the contract unless he does so within a reasonable time:

after he knew or ought to have known of the breach; or

after the expiration of any additional period of time fixed by the seller in accordance with Article 1797, or after the buyer has declared that he will not perform his obligations within such an additional period.