Gyms and Contracts

I just got thinking about a few things recently as I'd read of a gym closing down and dozens of members being left out of pocket for fees that they had paid in advance.

I was also interested from a contract perspective. At one gym, there was no written contract to my memory or even membership form but you got a receipt for whatever you paid, say €30 for 3 months. Where do these Gyms stand and should there be a contract for the use of the service?

I'm aware of verbal and implied contracts, but there's a lot of "if's" in it, because there's a certain amount of detail.

Should people be cautious that there is no mention of any contract, terms or conditions or anything else presented to them?