Vendor a retro in exercising right to repurchase

In cases of conventional redemption when the vendor a retro reserves the right to repurchase the property sold,[1] the parties to the sale must observe the parameters set forth by Article 1606 of the New Civil Code, which states:
Art. 1606. The right referred to in Article 1601, in the absence of an express agreement, shall last four years from the date of the contract.

Should there be an agreement, the period cannot exceed ten years.

However, the vendor may still exercise the right to repurchase within thirty days from the time final judgment was rendered in a civil action on the basis that the contract was a true sale with right to repurchase. (Emphasis supplied)
Thus, depending on whether the parties have agreed upon a specific period within which the vendor a retro may exercise his right to repurchase, the property subject of the sale may be redeemed only within the limits prescribed by the aforequoted provision.

[1] Article 1601 of the New Civil Code provides:

Art. 1601. Conventional redemption shall take place when the vendor reserves the right to repurchase the thing sold, with the obligation to comply with the provisions of Article 1616 and other stipulations which may have been agreed upon.