Stickers for your customers - did they actually appreciate it?

I want an easy way to thank my members who have been in Deutsch Gym for > 1 year. 

Laptop stickers (Sticker Mule) come to mind. 

If you have done this, did your customers actually appreciate it? In other words, was it worth the effort?

Stickers are dope, I'd say go for it! The potential word of mouth is worth the ~100 Euros you're going to spend.

that is what I was thinking, I could get an outsized reward for such a low cost

As a customer, I once was given a t-shirt from an error tracking service during my trial. I appreciate it and will keep choosing them for my side-projects :P
I think swag is appreciated.

And I found out they used this service:

thanks - they seem to be US based so shipping would probably be more as I'm in Germany, but the stuff looks nice

From my side, that t-shirt was shipped to Ukraine free of charge, but it took around two months

quite long but free is free :)