In Aspen Tech., Inc. v. Shasha, 253 S.W.3d 857 (Tex. App.--Houston 14th Dist. 2008, no pet.), the contract was Aspen Technology's fiscal year 2006 contract. Id. at 859. Under the 2006 contract, "the SVP Sales will be responsible for the periodic review of the plan and may make revisions from time to time." Id. at 862. The contract also provided, that "any additional terms or conditions, or verbal or written agreements between Shasha and Aspen will not apply unless explicitly agreed to and approved in a signed writing by both the SVP Sales and Shasha." Id. at 863 (bracketed language in original). In that case, Shasha argued that the contract was illusory because it allowed the SVP Sales to modify the contract from time to time. Id. at 862. The court disagreed, holding that the provision requiring a signed agreement between the parties on any additional terms or conditions controlled and prevented Aspen Technology from having unilateral authority to modify the contract. See id.at 863.