There is no obligation to participate in any specific exchange. That is, nobody can insist on you providing your services to them, whether for money, for local exchange currency, or for free, even when you are listed as a provider of such service. The whole system is based on a mutual agreement and a mutual benefit between the two parties. Both have to be happy with it. The provider of the service might currently have limited time, might not wish to sell anything at the time, or might not with to deal with you specifically. They might only wish to sell their services for money and not for local exchange currency. All of that is perfectly alright.
It is advisable that members of the network are clear on what they are available for and what they are not. This avoids the need for disappointing people who expects to be able to use your services. You can change your commitments at any time, and please make sure you update your profile when you change your mind.
Being a member of the Chalice Network implies a dedication to a high level of integrity. The network is something that we are creating together, and the more clean and integruous our interactions are, and the more trustworthy each of us are, the better everything will work for all of us.
By becoming a member you agree to have an open record in regards to other members. That is, others can record their experiences with you and state how satisfied or dissatisfied they are with your interactions. This is an additional incentive towards honesty and a high quality of service. If people are happy with what you do, others will quickly learn about it and seek your service as well. If they aren't, they won't.