When is it time to upgrade?
And is this function anything worth?

talking about subscription?

i did for the founder offer, right now wait for stonehenge

Upgrade weapons / armos and so on

It will only let you upgrade items to your level, if the upgrade requires a higher level it will tell you that you require more experience.

Upgrade weapons, but not armor.

Armor adds feed requirements for very little extra armor.

But weapons adds damage so always keep your weapons upped

In my opinion, it's not really worth upgrading armors because it increases feed requirements but doesn't really give much in return, just slightly increased defense/shield. Only thing I upgrade is my weapons for a little extra damage.