By Heather Somerville

SAN FRANCISCO, Dec 10 (Reuters) - Luxe, a startup that provides valet parking through an app, launched on Thursday a subscription service for all its users, as consumers increasingly turn to their smartphones for transportation at the press of a button.

Through the app, subscribers can pay a set monthly rate instead of per ride, an option the year-old company had previously tested with certain users.

"The speed at which this became an indispensable service for people ... is one of the things that we've been most pleased with," Phil Farhi, Luxe's vice president of product management, said in an interview. San Francisco-based Luxe's gross revenue is growing 40 percent per month, he added.

Farhi declined to share how many users Luxe has, but said 80 percent are repeat customers.

Drivers can use the Luxe app to order a valet - who arrive on scooter, skateboard or foot - to meet them at a destination and park their car. When the drivers need their car back, they use the app to alert the valet when and where to be met.

Subscriptions range from $139 to $799 per month, varying by city and customer need. For instance, New York residents tend to use their cars only on the weekend.

Luxe is also expanding its car-care service as a monthly subscription, Farhi said. The service includes oil changes, car washes and fuel-ups.

Luxe, which launched in October 2014, is available in New York, Los Angeles, San Francisco, Seattle, Chicago, Boston, Philadelphia and Austin, Texas. It has raised $25.5 million from investors.

Among Luxe's greatest challenges is convincing people to hand over one of their most valuable possessions to a stranger. Some customer reviews on business rating site Yelp, where Luxe has a 3.5-star rating, report valets damaging their vehicles.

The company has a $5 million insurance policy and parks cars only in garages or secured lots, where it rents spaces.

Luxe has about 70 employees and 1,000 valets, who are independent contractors. They will be reclassified as employees early next year, the company said.

(Editing by Stephen R. Trousdale and Richard Chang)