Whether it’s the end of a project or an individual job well done, it’s key to group cohesion that you celebrate those successes. And don’t be the only one to offer kudos and appreciation; encourage your team to celebrate without you as well.
By all means, arrange for a team lunch after the successful rollout of a new product or service, but then let them go out for drinks after work on their own. Doing so builds camaraderie, acts as an incentive for the next round of work, and reinforces the group cohesion you’ve already built.