In Curlee v. Walker, 112 Tex. 40, 244 S.W. 497 (Tex. 1929), the restrictive covenant was written so as to be in force for ten years from the date each piece of property was purchased. Curlee, 244 S.W. at 497. The court held that if a restrictive covenant is adopted by the owner of a tract of land as part of a general plan or scheme for the benefit of each purchaser of a part of that land, each purchaser, and his assigns, may enforce the covenant against any other purchaser or his assigns, until the covenant expires on the other purchaser's property. Curlee, 244 S.W. at 498. The restriction may only be enforced against a purchaser or his assign if he bought with actual or constructive knowledge of the general plan or scheme. Id. The supreme court held that if purchasers have conformed to the restrictions, "there surely could be no equity for them to demand the observance by the last one of his obligations . . . according to the plan." Curlee, 244 S.W. at 499. A purchaser who has abided by the restrictive covenant may enforce that covenant, even after it has expired on his property, against later purchasers, until it has expired on those later purchasers' properties. Id.