Good point。这正是我担心的。但是，

但是，如果不执行合约，他可能就会觉得有例可循，以后就不会准时交租了。

我今天已经告诉他，
The main purpose of this late fee is to make sure that the rent is paid on time. it is not my primary interest to collect the late fee。

希望他准时汇过来。