Although I found many alternatives, "provided" was the only one that fit. I'm looking for a single word. Example, "I would only use the program as long as it has a smartphone counterpart."
"If" and "when" can work in a lot sentences. You can go outside as long as you finish your homework. You can go outside if you finish your homework. You can go outside when you finish your homework. It's highly contextual. Do you have an example sentence? I doubt there's a whiz-bang word that will work better than a simple mechanic.
If or that/which I would only use the program if it has a smartphone counterpart I would only use a program that has a smartphone counterpart I would only use a program which has a smartphone counterpart
Provided is the best of what you're trying to do. Presuming/assuming are distant seconds. Simplicity is probably the way to go. "If" is hard to beat. You could roll it all together. I guess no one's said this? I would only use a program with a smartphone counterpart.
"Depending on whether [you, it, he, she, they. those,]....ör not." it rains they agree she shows up you sing those people he participates
