I founded my own software development company a couple of months ago. I was able to find a customer now (a smaller football club) that needs a custom software for tracking the staff, players, etc. Before I start working, I need my customer to sign my software contract which I got from my lawyer. The contract is basically ok, but one thing makes me think: The contract stipulates that the copyright of the software remains with my company and that the customer is not allowed to sub-licence it to other potential customers. However, I can sell the software to other potential customers if I want. But isn't that unfair to my customer? The customer needs to buy the software for a lot of money and in the end, is not able to make money with it. My lawyer said that this is ok and normal. Do you know if this is common practice? I don't want that my company gets a shady reputation over time.
I can sell the software to other potential customers if I want. But isn't that unfair to my customer?
That is subjective. That depends on the parties' intent, priorities, the pricing of the product, and so forth. From a legal standpoint, there is no requirement that contracts be symmetric or to establish the same rights & obligations to all parties.
You are not even imposing that clause. You are proposing it to your client as part of your offer, who will decide whether to accept the terms, require amendments, or decline the contract altogether. The sense of the client's decision will indicate that he considers the contract/clause(s) fair or unfair, accordingly.
Do you know if this is common practice?
It is very common. For instance, you are not allowed to sub-license the lawful copy of Windows OS you use.