Charles Ellicott Commentary Leviticus 25:30

"And if it be not redeemed within the space of a full year, then the house that is in the walled city shall be made sure in perpetuity to him that bought it, throughout his generations: it shall not go out in the jubilee." — Leviticus 25:30 (ASV)

if it is not redeemed within a full year. —This means redemption by either the vendor or his son. According to the interpretation that prevailed during the Second Temple, the phrase “full year” is used here for the seller’s benefit, since it gives him the advantage of an intercalary year. This provides an additional month, up to the last day of which he could still complete the redemption.

Furthermore, if the purchaser sometimes hid towards the end of the year to prevent the seller from redeeming his house, it was enacted that the original owner should hand over the redemption money to the public authorities if the purchaser could not be found. The owner could then break open the doors and take possession of the house. Also, if the purchaser died during the year, the vendor could redeem it from his heir.

It will not go out in the Jubilee. —If the vendor, however, failed to redeem the house within the prescribed period, it was not to be subject to the laws of the Jubilee like the land, but was to remain forever the property of the purchaser.