38 CFR §21.5745

1. (a)Veterans. The period of entitlement of a veteran expires on the first day following ten years from the date the veteran retires or is discharged or otherwise separated from active duty.
2. (b)Spouses, surviving spouses, and dependent children. If the veteran's or servicemember's entitlement is transferred, the period of entitlement of the spouse, surviving spouse, or dependent child expires 10 years from—
   1. (1)The date the veteran retires, is discharged or otherwise separated from active duty, or
   2. (2)If the servicemember dies on active duty, the date of the servicemember's death.