My NAL understanding is it doesn't matter if payment actually took place (otherwise how to enforce any normal sale transaction?), it's just whether an agreement

My NAL understanding is it doesn't matter if payment actually took place (otherwise how to enforce any normal sale transaction?), it's just whether an agreement that included consideration was in place. ie, the fact that the contract included consideration makes the contract valid. however if one side is in breach i think it's fair for the other side to go ahead and breach their responsibility also. in a case like this, anyway.