As far as I know there is no "standard" commercial (proprietary) End User License Agreement (EULA) that you can can download to include in your software. It is one of the benefits of the FLOSS community that there are licenses available that have been extensively checked by lawyers. And you could still consider using one of those, I will get back to that later.
You always should at the very least include your copyright notice which must be written in the form
name. The name must be a legal entity, which could be you personally, but it could also be your company (if it has been legally registered etc). It is unwise to assign copyright to a group name that has no legal status.
Adding a suitable End User License Agreement (EULA) in proprietary software is important for the following reasons:
- You must have asserted somewhere that people are buying (licensing) the use of your software, and not buying the code, intellectual property rights etc. If you do not mention this it would be unclear.
- You must have included disclaimers that whatever happens through the use of your software, you are not liable for any damages.
- You must have included some level of support (usually along the lines of: "you buy the software as-is and we may give or sell you updates later").
This is off the top of my head (and I am not a lawyer!), but you can see why that is important and why it needs to be in proper legalese just in case something goes wrong or one of your customers has malicious intent. It depends a little bit on what kind of software you are going to put in the market, but in general it is better to be safe than sorry. A EULA is there to protect you from the customer (read one by Microsoft or Apple just to get an idea). And they can be complex and risky to draft without the assistance of a lawyer.
There are a number of places where you can buy and download a EULA from online law-firm (or websites claiming to be), but unless you hire your own lawyer, you would still need to sift through the text carefully to make sure that all the different stipulations apply to you. The next best thing is to use what is available in the FLOSS world and modify them slightly so that you can serve your customers.
So coming back to the open source licenses: you can use one of the FLOSS licenses available and make modifications for paying customers, such as giving them permission for commercial use. The creative commons website is most clear on this (look at their explanation of "waivers"). You can do this because you are the owner (copyright holder) and you can set terms for you customers, something nobody else can do for your software and code. The Creative commons even have a variation of their licenses for this purpose: the creative commons plus license.
Whatever you do, take your time to think things through and read a lot before actually putting it out on the market. Asking Canonical for a standard Ubuntu EULA would also be helpful, maybe they have this and it would certainly make their software center more interesting.