I must admit that this mitzvah was one of the hardest for me to succeed in accomplishing. It took me decades to manage to count every single night until I made it to forty-nine, 49. I'd usually forget pretty early on. It started getting easier when I got a cellphone and was set up with a reminder service. Nowadays there are lots of email and cellphone apps and services you can sign up for. And they usually automatically consider you signed up each year without having to sign up again. But even that wasn't perfect, since my phone and computer are off on Friday Night, the Eve of the Sabbath plus the last night of Passover.
Then, finally, I came up with a homemade low-tech solution. I started posting a sign on the closet just across from where I sit while my husband is in shul, synagogue on Friday night. This helps me remember, thank Gd. I already have the sign up and waiting for this coming Thursday and Friday nights, the last night of Pesach and Leil Shabbat. Gd willing I will notice it on time to make the blessings.