[NolF]

Most licence terms already include a term to change the terms. So technically once you buy it, install it, and agree to it, you are also agreeing the terms may change. They probably also have arbitration clauses you are agreeing to so you can't directly sue them either.

[layer8]

That can’t be legally valid, because you wouldn’t know the future terms you’re now ostensibly agreeing to.

[NolF]

That's why they get you to agree to new terms and conditions with an update, or when there is a new TC you get a lovely email or whatever to ignore. Either you don't accept it so you don't get the update or you don't accept them and you can't continue to use the service if you don't accept the new terms.

The consideration for the change is getting the new features, updates, or using the services.