App design software

Hey,

I’m kind of good at drawing, and I’m training so I’ll become better, with this I would like to design my own software. Now I want to ask you people what softwares are standard in this field when it comes to software design and also what you maybe use? I know of illustrator but I don’t like monthly subscription. There’s XD which is free, and I have downloaded it, but I still need to check it out and see what the usage and possibilities are. I heard about Sketch, which looks very good, so do you think this app Sketch covers what I need? The logos and what not that needs to be drawn could be made in another program(I draw a lot using procreate but I got affinity designer as well), but for the putting together everything and making it look like the website/app I vision: is sketch the way to go?

Also from what I understand Sketch could be an once time payment. You only need to pay a renewed license if you want a new update, correct?

Thanks in advance, hope you can help me out!