I'm a PS Vita owner on FW 3.18, with the two exploit of GB & SS2.
Well happened that i already had the PS suite Dev and some game demo downloaded an backed up on my pc.

Copied again to the console, shows a little problem for running the two. The PS Suite Dev and the Runtime Package are out of date.
Problem is that i don't have (anymore, i suppose after re-setting the console once) the appropriate runtime to run the Game Demos i stored. I'm actually on Runtime 1.0, the far you can get without updating the console FW.
Yes because happened that the PSN let's you download the basic runtime package (1.0), but not the updates, and so the applications still can't run. We don't know what package should've installed in order to make this useful in the future...

Only solution to run the PSM Game appears to be updating the FW.
Re-assuming what he stated:
What you should do before June 2015:
Sign in to the PSM DevPortal with your PSN account
Click the button to “Apply for PSM Publisher License” and follow the directions
After you get approved, download SDK 1.21.02 (NOT SDK 2.00.00 or Unity for PSM)
Follow the directions to get the dev assistant for your Vita
Once everything is installed, play with a demo! For example, BallMazeDemo is pretty fun. Before the demo will run though, you have to generate an app key. Refer to PSM’s documentations for that.
Looks important to the cause to RUN ONCE AT LEAST a application. Well, i'm now wondering, it's worth enough for us 3.18 owners to update for it? I look forward for yours opinions, i hope this helped to summarize this problem that i suppose afflicts many's in this forum.

