Wash. Rev. Code § 68.46.075
In the event the beneficiary of a prearrangement contract make[s] no claim within fifty years of the date of the contract for the merchandise and services provided in the prearrangement contract, the funds deposited in the prearrangement trust for that contract, plus interest, shall be transferred to the cemetery authority's endowment fund, to be used for the purposes for which the endowment fund was established. However, the cemetery authority shall remain obligated for merchandise and services, unconstructed crypts, niches, and undeveloped property under the terms of the prearrangement contract. Claims may be made for merchandise and services, unconstructed crypts, niches, and undeveloped property on a prearrangement contract after the funds have been transferred to the endowment fund. These claims shall be paid for from the endowment fund income on a contract by contract basis.
RCW 68.46.075