I think the answer to this question is more philosophical than technical - that is, it's related to your personal ambitions and motivations rather than the technologies you can learn...
It depends entirely on what the software product is they're selling. Is it a product you believe in, is it a consultancy etc.
- How integral to the team can you become?
- What is the potential growth of the product?
- How large is the target market?
- What is the potential lifespan of the product?
- Does this product interest you on a personal level, i.e. do you find it interesting?
I've worked in positions where I spend much of my time "bored" and looking for stuff to do and in the end moving on. Of course, the more work I get, the less time I have to learn new technologies and less time to spend on R&D which is really what turns my crank. To the point that I sometimes spend time daydreaming about my past jobs where I'd have every afternoon to myself to do my own thing. Now I spend far too much time on projects for other people and not enough on projects for myself.
So really you have to stop and evaluate what is really important to you, be honest with yourself. If this company is small with potential for huge growth, can you help with that, will you be rewarded for that etc. or if this company is limited but will give you room for huge growth in an area that's important to you, then maybe it's a great place to stay.
If you want to get mired down in the drudgery of huge commitment, high pressure projects, and that is what excites you, maybe you need to move on.
There's two sides to my personality, and so far, I've not found an environment that can cater to them both - I thrive in high pressure environments with ridiculous deadlines providing solutions to "impossible" problems, in fact, this is an environment that in the past has set me aside from colleagues. However, that's not what I'm truly passionate about - I'm passionate about solving complex issues and studying fascinating concepts, even though I may not be up there with the Alan Kays of the world this is an area that really turns me on mentally.
The only person that can really answer your question fully is you, and in order to do that you really need to reflect on yourself and ask yourself the hard questions. Do you really enjoy what you do, be specific about what drives you and what turns you on. Only then can you really answer the question about what to do about it.
Edit: Alternatively you could think about a startup - perhaps you have ideas about a project you want to do, a problem that needs solving. Perhaps there's software out there that you use that you feel really isn't adequate, that could solve the target problem better than the current offerings. You could use your un/under utilized skillset to solve these problems and perhaps make it rich. Although, the chances of making it rich at a startup as they say is akin to winning the lottery - although, you have far more control over it than the lottery. It takes dogged persistence, a huge amount of self belief, the right contacts and the dedication and discipline to see it through. Startup life is not easy on you, and it's not easy on loved ones if you have them in your life, it's a risk involving a lot of hours and no guarantee of any pay off. But it could pay off in the realm of hundreds of thousands, or millions depending on what the project is.