Can i use FMS developer version for commercial purpose

If you refer to EULA of FMS you will see below text corresponding to Developer License:

.1.              Software  License.  Subject to the terms and conditions of this Agreement, Adobe grants to  Licensee a perpetual (except as set forth in Section 15) non-exclusive  license to install the Software on one (1) Computer  or Virtual Server and use  the Software delivered hereunder according to the terms and conditions of  this Agreement and the Documentation.  Unless indicated otherwise by the License  Key (as defined below) provided to Licensee, Licensee shall be deemed to have  licensed the Development Server. If Licensee has  licensed a Trial Version, in which case Section 2.2 applies, or if Licensee has  licensed Not For Resale Software, in which case Section 2.3 applies.

2.1.1.         Development  Server License.  This Section 2.1.1 applies only if Licensee  has obtained a valid Development Server license to the Software.  In addition to  the other terms contained herein, (a) Licensee’s license to the Development  Server Software is limited to a maximum number of (i) ten (10) Concurrent Connections when using with the Real Time Media  Protocol (RTMP), and (ii) fifty (50) Concurrent Connections when using the Real  Time Media Flow Protocol (RTMFP); and (b) Licensee shall not use the Development  Server for load balancing.  No maintenance and support is available for the  Development Server.   

So as per EULA you can use Developer Edition for commercial purpose with restriction that it cannot be used for load balancing or creating cluster of Developer Edition Network.

You can refer to this old article when this part of EULA was introduced: http://www.flashcomguru.com/index.cfm/2006/10/9/fmsdevedition