I lost commander when I bough premium is that a glitch or is that supposed to happen? if not please give me it back

 

That is supposed to happened. It is not a glitch.

 

Technically you didn't lose it, you lost the commander tag.
Unless you lost the kit as well.
In which case, idk

 

You still have the permissions of a commander, you just lose to prefix next to your name.

 

This is correct, to get the tag back buy it again or email [email protected] and request the tag to be given back with proof of buying it