Foursquare is getting some help from Microsoft as it seeks to turn its location-based mobile app into a sustainable business.

Microsoft has invested $15 million and agreed to a strategic partnership with the New York-based startup, Chief Executive Dennis Crowley said in an interview. The investment will be added to the $35 million investment round Foursquare announced last December and which valued the company at about $650 million. In addition to an equity investment, Microsoft has signed a multi-year contract to license Foursquare data in services such as its mobile operating system and Bing search engine.