If i restore my iphone 5s will i loose my t-moblie service?

Will i have to go to the store and activate it again?

No you won't.

Yes you will lose everything even if backed up the best thing to do is sale it and get a new phone

You won't loose your tmobile service. The only thing that will happen when restoring your iPhone is your contacts, games and apps will be erased as well as any pictures and or music UNLESS you back your phone up into icloud/itunes. Hope this helps!

Short answer… No! Don't worry, Kevins answer is spot on