Need help with trigger

i can limit a building to one but when it upgrades, the limit goes away.. how can i make it so it does'nt go away?

After it upgrades limit it to zero.

Edit: There also might be some equivalency things you can mess with, but I don't think so.

It goes away cuz that unit it's no longer the same.

i know, so how can i make it the same

Dependency equivalents
In object editor